Ribbon Communications (RBBN) 10-K28 Feb 242023 FY Annual reportFinancial data

Company Profile

Cover

Cover - USD ($) $ in Thousands	12 Months Ended
Cover - USD ($) $ in Thousands	Dec. 31, 2023	Feb. 23, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38267
Entity Registrant Name	RIBBON COMMUNICATIONS INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1669692
Entity Address, Address Line One	6500 Chase Oaks Boulevard, Suite 100
Entity Address, City or Town	Plano
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	75023
City Area Code	978
Local Phone Number	614-8100
Title of 12(b) Security	Common Stock, par value $0.0001
Trading Symbol	RBBN
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 199,304
Entity Common Stock, Shares Outstanding		172,461,725
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the definitive Proxy Statement to be delivered to stockholders in connection with the registrant's 2024 Annual Meeting of Stockholders are incorporated by reference into Part III of this report.
Entity Central Index Key	0001708055
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	34
Auditor Name	Deloitte & Touche LLP
Auditor Location	Dallas, Texas

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 26,630	$ 67,262
Accounts receivable, net	268,421	267,244
Inventory	77,521	75,423
Other current assets	46,146	68,057
Total current assets	418,718	477,986
Property and equipment, net	41,820	44,832
Intangible assets, net	238,087	294,728
Goodwill	300,892	300,892
Deferred income taxes	69,761	53,649
Operating lease right-of-use assets	39,783	44,888
Other assets	35,092	38,589
Total assets	1,144,153	1,255,564
Current liabilities:
Current portion of term debt	35,102	20,058
Accounts payable	85,164	95,810
Accrued expenses and other	91,687	85,270
Operating lease liabilities	15,739	15,416
Deferred revenue	113,381	113,939
Total current liabilities	341,073	330,493
Long-term debt, net of current	197,482	306,270
Warrant liability	5,295	0
Preferred stock liability, $0.01 par value per share; 10,000,000 shares authorized, 55,000 shares issued and outstanding at December 31, 2023 ($56,650 liquidation preference); none issued and outstanding at December 31, 2022	53,337	0
Operating lease liabilities, net of current	38,711	46,183
Deferred revenue, net of current	19,218	19,254
Deferred income taxes	5,616	3,750
Other long-term liabilities	30,658	31,187
Total liabilities	691,390	737,137
Commitments and contingencies
Stockholders' equity:
Common stock, 240,000,000 shares authorized, $0.0001 par value, 172,083,667 shares issued and outstanding at December 31, 2023; 168,324,995 shares issued and outstanding at December 31, 2022	17	17
Additional paid-in capital	1,958,909	1,941,569
Accumulated deficit	(1,519,950)	(1,453,744)
Accumulated other comprehensive income	13,787	30,585
Total stockholders' equity	452,763	518,427
Total liabilities and stockholders' equity	$ 1,144,153	$ 1,255,564

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, liquidation preference, value		$ 56,650
Preferred stock, shares issued (in shares)	55,000	0
Preferred stock, shares outstanding (in shares)	55,000	0
Common stock, shares authorized (in shares)	240,000,000	240,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)	172,083,667	168,324,995
Common stock, shares outstanding (in shares)	172,083,667	168,324,995

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue:
Total revenue	$ 826,339,000	$ 819,760,000	$ 844,957,000
Cost of revenue:
Total cost of revenue	418,256,000	418,824,000	400,297,000
Gross profit	408,083,000	400,936,000	444,660,000
Operating expenses:
Research and development	190,660,000	203,676,000	194,948,000
Sales and marketing	137,460,000	147,766,000	150,279,000
General and administrative	54,962,000	51,053,000	53,661,000
Amortization of acquired intangible assets	28,601,000	29,646,000	28,283,000
Impairment of goodwill	0	0	116,000,000
Acquisition-, disposal- and integration-related	4,476,000	6,286,000	7,632,000
Restructuring and related	16,209,000	10,833,000	11,653,000
Total operating expenses	432,368,000	449,260,000	562,456,000
Loss from operations	(24,285,000)	(48,324,000)	(117,796,000)
Interest expense, net	(27,320,000)	(19,780,000)	(15,831,000)
Other expense, net	(3,768,000)	(44,495,000)	(74,516,000)
Loss before income taxes	(55,373,000)	(112,599,000)	(208,143,000)
Income tax (provision) benefit	(10,833,000)	14,516,000	30,958,000
Net loss	$ (66,206,000)	$ (98,083,000)	$ (177,185,000)
Loss per share:
Basic (in dollars per share)	$ (0.39)	$ (0.63)	$ (1.20)
Diluted (in dollars per share)	$ (0.39)	$ (0.63)	$ (1.20)
Shares used to compute loss per share:
Basic (in shares)	170,408	156,668	147,575
Diluted (in shares)	170,408	156,668	147,575
Product
Revenue:
Total revenue	$ 445,150,000	$ 442,680,000	$ 453,042,000
Cost of revenue:
Total cost of revenue	250,609,000	245,145,000	214,745,000
Service
Revenue:
Total revenue	381,189,000	377,080,000	391,915,000
Cost of revenue:
Total cost of revenue	139,357,000	142,137,000	147,209,000
Amortization of acquired technology
Cost of revenue:
Total cost of revenue	$ 28,290,000	$ 31,542,000	$ 38,343,000

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (66,206)	$ (98,083)	$ (177,185)
Other comprehensive income (loss), net of tax:
Unrealized gain (loss) on interest rate swap, net of reclassifications and amortization into earnings	(10,015)	19,321	12,759
Reclassification of gain to other expense, net upon sale of interest rate swap	(5,099)	0	0
Foreign currency translation adjustments	(506)	(792)	(239)
Employee retirement benefits	(1,178)	4,478	0
Other comprehensive income (loss), net of tax	(16,798)	23,007	12,520
Comprehensive loss, net of tax	$ (83,004)	$ (75,076)	$ (164,665)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Additional Paid-in Capital	Accumulated deficit	Accumulated other comprehensive (loss) income
Beginning balance (in shares) at Dec. 31, 2020		145,425,248
Beginning balance at Dec. 31, 2020	$ 686,853	$ 15	$ 1,870,256	$ (1,178,476)	$ (4,942)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)		13,815
Exercise of stock options	24		24
Vesting of restricted stock awards and units (in shares)		3,653,552
Vesting of restricted stock awards and units	0
Vesting of performance-based stock units (in shares)		1,557,656
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations (in shares)		(1,754,963)
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	(14,464)		(14,464)
Stock-based compensation expense	19,418		19,418
Other comprehensive income (loss)	12,520				12,520
Net loss	(177,185)			(177,185)
Ending balance (in shares) at Dec. 31, 2021		148,895,308
Ending balance at Dec. 31, 2021	527,166	$ 15	1,875,234	(1,355,661)	7,578
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)		708
Exercise of stock options	1		1
Vesting of restricted stock awards and units (in shares)		3,075,543
Vesting of restricted stock awards and units	0
Vesting of performance-based stock units (in shares)		179,184
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations (in shares)		(897,059)
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	(2,784)		(2,784)
Common stock issued in equity offering (in shares)		17,071,311
Common stock issued in equity offering	52,067	$ 2	52,065
Issuance costs related to equity offering	(1,654)		(1,654)
Stock-based compensation expense	18,707		18,707
Other comprehensive income (loss)	23,007				23,007
Net loss	$ (98,083)			(98,083)
Ending balance (in shares) at Dec. 31, 2022	168,324,995	168,324,995
Ending balance at Dec. 31, 2022	$ 518,427	$ 17	1,941,569	(1,453,744)	30,585
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)		7,816
Exercise of stock options	15		15
Vesting of restricted stock awards and units (in shares)		4,840,738
Vesting of restricted stock awards and units	0
Vesting of performance-based stock units (in shares)		381,071
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations (in shares)		(1,470,953)
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	(4,481)		(4,481)
Stock-based compensation expense	21,806		21,806
Other comprehensive income (loss)	(16,798)				(16,798)
Net loss	$ (66,206)			(66,206)
Ending balance (in shares) at Dec. 31, 2023	172,083,667	172,083,667
Ending balance at Dec. 31, 2023	$ 452,763	$ 17	$ 1,958,909	$ (1,519,950)	$ 13,787

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (66,206)	$ (98,083)	$ (177,185)
Adjustments to reconcile net loss to cash flows (used in) provided by operating activities:
Depreciation and amortization of property and equipment	14,105	15,295	16,962
Amortization of intangible assets	56,891	61,188	66,626
Amortization of debt issuance costs	3,241	2,308	4,763
Amortization of accumulated other comprehensive gain related to interest rate swap	(5,575)	0	0
Stock-based compensation	21,806	18,707	19,418
Impairment of goodwill	0	0	116,000
Deferred income taxes	(9,196)	(18,251)	(45,596)
Gain on sale of business	0	(62)	(2,772)
Decrease in fair value of investments	0	41,291	71,252
Gain on sale of swap	(7,301)	0	0
Change in fair value of warrant liability	(201)	0	0
Change in fair value of preferred stock liability	1,548	0	0
Dividends accrued on preferred stock liability	3,935	0	0
Foreign currency exchange losses	(44)	1,576	5,002
Changes in operating assets and liabilities:
Accounts receivable	5,726	14,285	(47,279)
Inventory	(10,701)	(32,099)	(9,029)
Other operating assets	34,834	2,109	9,958
Accounts payable	(10,498)	(448)	34,482
Accrued expenses and other long-term liabilities	(14,684)	(37,635)	(50,324)
Deferred revenue	(593)	3,455	6,904
Net cash provided by (used in) operating activities	17,087	(26,364)	19,182
Cash flows from investing activities:
Purchases of property and equipment	(9,381)	(10,254)	(17,132)
Purchases of software licenses	(100)	(3,300)	0
Proceeds from sale of business	0	1,418	2,944
Net cash used in investing activities	(9,481)	(12,136)	(14,188)
Cash flows from financing activities:
Borrowings under revolving line of credit	97,000	73,625	0
Principal payments on revolving line of credit	(97,000)	(73,625)	0
Proceeds from issuance of long-term debt	0	0	74,625
Principal payments of term debt	(95,058)	(45,058)	(92,176)
Principal payments of finance leases	0	(595)	(903)
Payment of debt issuance costs	(1,685)	(1,046)	(789)
Proceeds from equity offering	0	52,067	0
Payment of equity offering issuance costs	0	(1,654)	0
Proceeds from issuance of preferred stock and warrant liabilities	53,350	0	0
Proceeds from the exercise of stock options	15	1	24
Payment of tax withholding obligations related to net share settlements of restricted stock awards	(4,481)	(2,784)	(14,464)
Net cash (used in) provided by financing activities	(47,859)	931	(33,683)
Effect of exchange rate changes on cash and cash equivalents	(379)	(1,654)	(523)
Net decrease in cash and cash equivalents	(40,632)	(39,223)	(29,212)
Cash and cash equivalents, beginning of year	67,262	106,485	135,697
Cash and cash equivalents, end of year	26,630	67,262	106,485
Supplemental disclosure of cash flow information:
Interest paid	25,573	19,336	14,867
Income taxes paid	18,876	16,988	14,447
Income tax refunds received	1,611	1,251	1,488
Supplemental disclosure of non-cash investing activities:
Capital expenditures incurred, but not yet paid	2,578	2,559	2,269
Inventory transfers to property and equipment	1,693	2,896	676
Software license acquired through investment disposal	0	1,886	0
Supplemental disclosure of non-cash financing activities:
Total fair value of restricted stock awards, restricted stock units, and performance-based stock units on date vested	$ 15,571	$ 9,858	$ 40,751

NATURE OF THE BUSINESS

NATURE OF THE BUSINESS	12 Months Ended
NATURE OF THE BUSINESS	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF THE BUSINESS	NATURE OF THE BUSINESS Ribbon Communications Inc. ("Ribbon" or the "Company") is a leading global provider of communications technology to service providers and enterprises. The Company provides a broad range of software and high-performance hardware products, network solutions, and services that enable the secure delivery of data and voice communications, and high-bandwidth networking and connectivity for residential consumers and for small, medium, and large enterprises and industry verticals such as finance, education, government, utilities, and transportation. Ribbon's mission is to create a recognized global technology leader providing cloud-centric solutions that enable the secure exchange of information, with unparalleled scale, performance, and elasticity. The Company is headquartered in Plano, Texas, and has a global presence with research and development, or sales and support locations in over thirty countries around the world.

BASIS OF PRESENTATION AND SUMMA

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The consolidated financial statements have been prepared in United States dollars, in accordance with accounting principles generally accepted in the United States ("GAAP"). Private Placement Offering On March 28 , 2023, the Company issued 55,000 shares of newly designated Series A Preferred Stock (the "Preferred Stock") to investors in a private placement offering at a price of $970 per share, along with 4.9 million warrants (the "Warrants") to purchase shares of the Company's common stock, par value $0.0001 per share (the "Private Placement"), at the exercise price of $3.77 per share. The proceeds from the Private Placement were approximately $53.4 million, including approximately $10 million from existing related party stockholders (See Note 16). Equity Offering On August 12, 2022, the Company entered into a Securities Purchase Agreement with certain investors for the sale (the "Equity Offering") in a private placement by the Company of 17,071,311 shares (the "Shares") of the Company’s common stock, par value $0.0001 per share, at a price of $3.05 per share. The aggregate gross proceeds from the Equity Offering were approximately $52.1 million, including $10.0 million from existing related party shareholders, before deducting offering expenses paid by the Company of approximately $1.7 million. The original issuance of the Shares in the Equity Offering was exempt from the registration requirements of the Securities Act of 1933, as amended (the “Securities Act”). The Company subsequently filed a registration statement on Form S-3 (the “Registration Statement”) with the SEC registering the Shares, which Registration Statement was declared effective by the SEC on September 23, 2022. Operating Segments The Company's chief operating decision maker (the "CODM") is its president and chief executive officer. The CODM assesses the Company's performance based on the performance of two separate organizations within Ribbon: the Cloud and Edge segment ("Cloud and Edge") and the IP Optical Networks segment ("IP Optical Networks"). Significant Accounting Policies Principles of Consolidation The accompanying consolidated financial statements include the accounts of Ribbon and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Use of Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and judgments relied upon in preparing these consolidated financial statements include accounting for business combinations, revenue recognition for multiple element arrangements, inventory valuations, assumptions used to determine the fair value of stock-based compensation and the Preferred Stock and Warrants, intangible asset and goodwill valuations, including impairments, debentures and warrants , warranty accruals, legal contingencies and recoverability of Ribbon's net deferred tax assets and the related valuation allowances. Ribbon regularly assesses these estimates and records changes in estimates in the period in which they become known. Ribbon bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates. Reclassifications Certain reclassifications, not affecting previously reported net income (loss), have been made to the previously issued financial statements to conform to the current year presentation. Business Combinations The Company recognizes identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at the acquisition date, its estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill to the extent that it identifies adjustments to the preliminary purchase price allocation. Upon the conclusion of the measurement period or final determination of the values of assets acquired and liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations. Revenue Recognition The Company derives revenue from two primary sources: products and services. Product revenue includes the Company's hardware and software that function together to deliver the products' essential functionality. Software and hardware are also sold on a standalone basis. Services include customer support (software updates, upgrades and technical support), consulting, design services, installation services and training. Generally, contracts with customers contain multiple performance obligations, consisting of products and services. For these contracts, the Company accounts for individual performance obligations separately if they are considered distinct. When an arrangement contains more than one performance obligation, the Company will allocate the transaction price to each performance obligation on a relative standalone selling price basis. The Company utilizes the observable price of goods and services, including when they are sold separately to similar customers, in order to estimate standalone selling price. The Company's software licenses typically provide a perpetual right to use the Company's software. The Company also sells term-based software licenses that expire and Software-as-a-Service ("SaaS")-based software which are referred to as subscription arrangements. The Company does not customize its software nor are installation services required, as the customer has a right to utilize internal resources or a third-party service company. The software and hardware are delivered before related services are provided and are functional without professional services or customer support. The Company has concluded that its software licenses are functional intellectual property that are distinct, as the user can benefit from the software on its own. Product revenue is typically recognized upon transfer of control or when the software is made available for download, as this is the point the user of the software can direct the use of, and obtain substantially all of the remaining benefits from, the functional intellectual property. The Company begins to recognize software revenue related to the renewal of subscription software licenses at the start of the subscription period. The Company offers warranties on its products. Certain of the Company's warranties are considered to be assurance-type in nature, ensuring the product is functioning as intended. Assurance-type warranties do not represent separate performance obligations. The Company also sells separately-priced maintenance service contracts which qualify as service-type warranties and represent separate performance obligations. The Company does not allow and has no history of accepting product returns. Services revenue includes revenue from customer support and other professional services. Customer support includes software updates on a when-and-if-available basis, telephone support, integrated web-based support and bug fixes or patches. The Company sells its customer support contracts at a percentage of list or net product price. Customer support revenue is recognized ratably over the term of the customer support agreement, which is typically one year. The Company's professional services include consulting, technical support, resident engineer services, design services and installation services. Because control transfers over time, revenue is recognized based on progress toward completion of the performance obligation. The method to measure progress toward completion requires judgment and is based on the nature of the products or services to be provided. The Company generally uses the input method to measure progress for its contracts because it believes such method best depicts the transfer of assets to the customer, which occurs as the Company incurs costs for the contracts. However, in some instances, the Company uses the output method because it best depicts the transfer of asset to the customer. Under the cost-to-cost measure of progress, the progress toward completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. When the measure of progress is based upon expended labor, progress toward completion is measured as the ratio of labor time expended to date versus the total estimated labor time required to complete the performance obligation. Revenue is recorded proportionally as costs are incurred or as labor is expended. Costs to fulfill these obligations include internal labor as well as subcontractor costs. Customer training includes courses offered by the Company. The related revenue is typically recognized as the training services are performed. Preferred Stock and Warrants The Company accounts for the Preferred Stock and Warrants as liability-classified instruments based on an assessment of their specific terms in accordance with ASC Topic 480, Distinguishing Liabilities from Equity . The fair value option was elected for the Preferred Stock, as the Company considers fair value to best reflect the expected future economic value. These liabilities are remeasured to fair value at each reporting date using the same valuation methodology applied upon issuance. The Preferred Stock is considered to be debt for our Consolidated Net Leverage Ratio covenant calculation required under our 2020 Credit Facility. The value of the Preferred Stock is calculated using the Black-Derman-Toy (BDT) stochastic yield lattice model to capture the optimal timing of repayment, increasing dividend rate and other features, and the value of the Warrants is calculated using the Black-Scholes Pricing Model. Changes in the fair value of the Preferred Stock and Warrants are reported as Other expense, net in the Company's consolidated statements of operations. Financial Instruments The carrying amounts of the Company's cash equivalents, accounts receivable, accounts payable and borrowings under a revolving credit facility in the Consolidated Balance Sheets approximates fair value due to the immediate or short-term nature of these financial instruments. Ribbon's term debt balance as of December 31, 2023 and 2022 of $235.4 million and $330.4 million, respectively, had a fair value of approximately $235.1 million and $323.0 million , respectively. Our Preferred Stock and Warrants liabilities as of December 31, 2023 had a combined fair value of $58.6 million , including cumulative dividends on the Preferred Stock of $3.9 million . Financial instruments with remaining maturities or that are due within one year from the balance sheet date are classified as current. Financial instruments with maturities or that are payable more than one year from the balance sheet date are classified as noncurrent. Fair Value Option - Investment in AVCT The Company received debentures (the "Debentures") and warrants (the "AVCT Warrants") as sale consideration in connection with its December 1, 2020 sale of the Kandy Communications Business to American Virtual Cloud Technologies, Inc. ("AVCT") (the "Kandy Sale"). On September 8, 2021 (the "Debenture Conversion Date"), the Debentures were converted into 13,700,421 shares of AVCT common stock (the "Debenture Shares"). In connection with the conversion of the Debentures to the Debenture Shares, the Company elected to use the fair value option to account for its equity investment in AVCT as permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), which then refers to ASC 820, Fair Value Measurement ("ASC 820") to provide the fair value framework for valuing such investments. In accordance with ASC 820, the Company recorded the investment in AVCT at fair value, with changes in fair value recorded as a component of Other (expense) income, net, in the consolidated statements of operations. See Note 4 for a discussion of the valuation of the Debentures, AVCT warrants and Debenture Shares. On August 29, 2022, the Company and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of the Company's investment in the Debenture Shares and the AVCT Warrants with an aggregate fair value of $2.6 million. See Note 4 for a description of the settlement agreement with AVCT. Transfers of Financial Assets The Company's IP Optical Networks segment maintains customer receivables factoring agreements with a number of financial institutions. Under the terms of these agreements, the Company may transfer receivables to the financial institutions, on a non-recourse basis, provided that the financial institutions approve the receivables in advance. The Company maintains credit insurance policies from major insurance providers or obtains letters of credit from the customers for a majority of its factored trade receivables. The Company accounts for the factoring of its financial assets as a sale of the assets and records the factoring fees, when incurred, as a component of interest expense in the consolidated statements of operations, and the proceeds from the sales of receivables are included in cash from operating activities in the consolidated statements of cash flows. Factoring of accounts receivable and associated fees for the years ended December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Accounts receivable sold $ 106,705 $ 74,523 Less factoring fees (2,736) (1,085) Net cash proceeds $ 103,969 $ 73,438 Foreign Currency Translation For foreign subsidiaries where the functional currency is the local currency, assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Revenue and expenses are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Accumulated other comprehensive income. For foreign subsidiaries where the functional currency is the U.S. dollar, monetary assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are remeasured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Other expense, net. Realized and unrealized foreign currency exchange gains and losses arising from transactions denominated in currencies other than the subsidiary's functional currency are reflected in earnings. The Company records its foreign currency gains (losses) as a component of Other expense, net. The Company recognized net foreign currency losses of less than $0.1 million, $1.6 million and $5.0 million for the years ended December 31, 2023, 2022 and 2021, respectively. Inventory Inventory is recorded at the lower of cost or market value using the first-in, first-out convention. The Company reduces the carrying value of inventory for those items that are potentially excess, obsolete or slow-moving based on changes in customer demand, technology developments or other economic factors. Ribbon writes down evaluation equipment (equipment at customer sites for testing and evaluation) at the time of shipment to its customers, as it is probable that the inventory value will not be realized. Deferred product costs represent deferred cost of revenue for product shipments to customers prior to satisfaction of Ribbon's revenue recognition criteria. The Company classifies inventory that is not expected to be consumed within one year from the balance sheet date as noncurrent and includes such inventory as a component of Other assets. Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, which range from two Software development costs associated with internal use software are incurred in three stages of development: the preliminary project stage, the application development stage and the post-implementation stage. Costs incurred during the preliminary project and post-implementation stages are expensed as incurred. Certain qualifying costs incurred during the application development stage are capitalized as property and equipment. Internal use software is amortized on a straight-line basis over its estimated useful life of three years, beginning when the software is ready for its intended use. Intangible Assets and Goodwill The Company's intangible assets are comprised of in-process research and development, developed technology, customer relationships, trade names, and internal use software. Intangible assets are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable based upon the estimated undiscounted cash flows. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by a comparison of the carrying amount of an asset or asset group to future net undiscounted cash flows expected to be generated by the asset or asset group. If these comparisons indicate that an asset is not recoverable, the Company will recognize an impairment loss for the amount by which the carrying value of the asset or asset group exceeds the related estimated fair value. Estimated fair value is based on either discounted future operating cash flows or appraised values, depending on the nature of the asset. The Company amortizes its intangible assets over their respective useful lives, with the exception of in-process research and development, which has an indefinite life until the product is generally available, at which time such asset is typically reclassified to developed technology, and the Company begins to amortize this asset. See Note 10 for additional information regarding the Company's intangible assets. Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. Goodwill is not amortized, but instead is tested for impairment at least annually, or more frequently if indicators of potential impairment exist, by comparing the fair value of the Company's reporting unit to its carrying value. The Company's annual test for impairment of goodwill is completed as of October 1. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may either be an operating segment or a portion of an operating segment. The Company's reporting units are its two operating segments, Cloud and Edge and IP Optical Networks. The Company performs a fair value analysis for each reporting unit using both an income and market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. The Company assesses each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately. Any impairment charges are reported separately in the Company's consolidated statements of operations. Stock-Based Compensation The Company's stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period, and includes an estimate of the awards that will be forfeited. The Company uses the Black-Scholes valuation model for estimating the fair value of stock options on the grant date. The fair value of stock option awards is affected by the Company's stock price as well as valuation assumptions, including the volatility of Ribbon's stock price, expected term of the option, risk-free interest rate and expected dividends. The Company may grant to certain of its executives and certain other employees performance-based stock units ("PSUs") that include a market condition. The Company uses a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values of the PSUs. The Company is required to record expense for the PSUs with market conditions through their respective final vesting dates regardless of the number of shares that are ultimately earned. Once the grant date criteria have been met for a fiscal year performance period, the Company records stock-based compensation expense based on its assessment of the probability that the respective performance condition will be achieved and the level, if any, of such achievement. The Compensation Committee determines the number of shares earned, if any, after the Company's financial results for each fiscal year performance period are finalized. Upon the determination by the Compensation Committee of the number of shares that will be received upon vesting, such number of shares becomes fixed and the unamortized expense is recorded through the remainder of the service period, at which time any Performance PSUs earned, will vest pending each executive's continued employment with the Company through that date. Concentration of Risk The financial instruments that potentially subject Ribbon to concentrations of credit risk are cash and accounts receivable. The Company's cash equivalents were managed by one financial institution at December 31, 2023 . Historically, the Company has not experienced significant losses due to such bank depository concentration. Certain components and software licenses from third parties used in Ribbon's products are procured from single sources of supply. The failure of a supplier, including a subcontractor, to deliver on schedule could delay or interrupt Ribbon's delivery of products and thereby materially adversely affect Ribbon's revenue and operating results. Advertising Costs Advertising costs are expensed as incurred and included as a component of Sales and marketing expense in the Company's consolidated statements of operations. Advertising expenses were $1.2 million , $1.5 million and $1.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. Loss Contingencies and Reserves Ribbon is subject to ongoing business risks arising in the ordinary course of business, including legal claims, that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. Ribbon regularly evaluates current information available to determine whether such amounts should be adjusted and records changes in estimates in the period they become known. An allowance for doubtful accounts is estimated based on the Company's assessment of the collectability of specific customer accounts. Ribbon accrues for royalties for technology that it licenses from vendors based on established royalty rates and usage. Ribbon is periodically contacted by third parties who claim that Ribbon's products infringe on certain intellectual property of a third party. Ribbon evaluates these claims and accrues amounts when it is probable that the obligation has been incurred and the amounts are reasonably estimable. Warranty The Company records warranty liabilities for estimated costs of fulfilling its obligations under standard limited hardware and software warranties at the time of sale. The specific warranty terms and conditions vary depending upon the country in which the Company does business, but generally includes material costs, technical support, labor and associated overhead over a period ranging from one At December 31, 2023, the Company's liability for product warranties was $12.2 million of which $5.4 million was current and included in Accrued expenses and other and $6.8 million was long-term and included in Other long-term liabilities in the Company's consolidated balance sheet. At December 31, 2022, the Company's liability for product warranties was $11.9 million, of which $5.3 million was current and included in Accrued expenses and other, and $6.6 million was long-term and included in Other long-term liabilities in the Company's consolidated balance sheet. Research and Development Grants The Company records grants received from the Office of the Innovation Authority of the Israeli Ministry of Economics (the "IIA") as a reduction to Research and development expense. Royalties payable to the IIA are recognized pursuant to sales of related products and are included in Cost of revenue - product (see Note 26). Accounting for Leases The Company accounts for its leases in accordance with Accounting Standards Codification ("ASC") 842, Leases ("ASC 842") (see Note 21). The Company has operating leases for corporate offices, and research and development facilities. Operating leases are reported separately in the Company's consolidated balance sheets at December 31, 2023 and 2022. The Company has no finance leases as of December 31, 2023 or 2022. The Company determines if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides the Company with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, the Company does not separate lease and non-lease components but rather, accounts for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. Lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases would include both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. The Company expenses all variable lease costs as incurred. Accounting for Income Taxes Deferred tax assets and liabilities are recognized for the expected future consequences of events that have been reflected in the consolidated financial statements. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and operating loss carryforwards, using tax rates expected to be in effect for the years in which the differences are expected to reverse. The Company records valuation allowances to reduce deferred income tax assets to the amount that is more likely than not to be realized. The Company has provided for income taxes on the undistributed earnings of its non-U.S. subsidiaries as of December 31, 2023, excluding Ireland and Israel, which are indefinitely reinvested. Accordingly, the Company is required to recognize and record deferred taxes for 2023 on the entire outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, no amount of the benefit attributable to the position is recognized. The tax benefit to be recognized of any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. Defined Benefit Plans The Company has defined benefit plans for some of its employees at various international locations. The Company recognizes retirement benefit assets or liabilities in the consolidated balance sheets reflecting the funded status of pension and other retirement benefit plans. Retirement benefit assets and liabilities are adjusted for the difference between the benefit obligations and the plan assets at fair value (measured at year-end), with the offset recorded directly to stockholders' equity through Other comprehensive income (loss), net of tax. The amount recorded in stockholders' equity represents the after-tax unamortized actuarial gains or losses, unamortized transition obligations and unamortized prior service costs. Recent Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (the "FASB") issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which increases the disclosure requirements around rate reconciliation information and certain types of income taxes companies are required to pay. ASU 2023-09 will be effective for the Company beginning in 2025, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which improves reportable segment disclosure requirements, including enhancement of the disclosures of significant segment expenses and interim disclosure requirements, to enable investors to better understand an entity's overall performance and assess potential future cash flows. ASU 2023-07 will be effective for the Company annually beginning in 2024 and on an interim basis beginning in 2025, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC's disclosure Update and Simplification Initiative (“ASU 2023-06”), which amends the disclosure or presentation requirements related to various subtopics in the FASB Accounting Standards Codification. This ASU was issued in response to and to align GAAP with the SEC's August 2018 final rule that updates and simplifies disclosure requirements. The effective date for the Company for each amendment will be the date on which the SEC's removal of that related disclosure requirement becomes effective, with early adoption prohibited. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. On February 1, 2023, the FASB staff noted that they believe that the Pillar 2 tax, established by the OECD and intended to apply for tax years beginning in 2024, would be an alternative minimum tax and therefore deferred tax assets would not need to be recognized related to this parallel taxing system. On Febru

BUSINESS ACQUISITIONS

BUSINESS ACQUISITIONS	12 Months Ended
BUSINESS ACQUISITIONS	Dec. 31, 2023
Business Combinations [Abstract]
BUSINESS ACQUISITIONS	BUSINESS ACQUISITIONS On March 3, 2020, Ribbon completed its merger transaction with ECI Telecom Group Ltd ("ECI") in accordance with the terms of the Agreement and Plan of Merger, dated as of November 14, 2019 (the "ECI Acquisition"). Prior to the ECI Acquisition, ECI was a privately-held global provider of end-to-end packet optical transport and software-defined networking ("SDN") and network function virtualization solutions for service providers, enterprises and data center operators. The ECI Acquisition was accounted for as a business combination and the financial results of ECI are included in the Company's consolidated financial statements. Costs related to the integration of the Company and ECI are included in the Acquisition-, disposal- and integration-related expenses in the table below. Acquisition-, Disposal- and Integration-Related Expenses Acquisition-related expenses include those expenses related to acquisitions that would otherwise not have been incurred by the Company, including professional and services fees, such as legal, audit, consulting, paying agent and other fees, and expenses related to cash payments to certain former executives of the acquired businesses in connection with their employment agreements. Disposal-related expenses are professional and services fees related to disposals of subsidiaries or portions of the business. Integration-related expenses represent incremental costs related to combining the Company and its business acquisitions, such as third-party consulting and other third-party services related to merging the previously separate companies' systems and processes. The disposal-related expenses in the year ended December 31, 2022 primarily relate to costs incurred from the sale of one of our foreign subsidiaries. The disposal-related expenses in the year ended December 31, 2021 relate to the Kandy Sale (as defined below). The integration-related expenses in the years ended December 31, 2023, 2022 and 2021 relate to the ECI Acquisition. The components of Acquisition-, disposal- and integration-related expenses incurred in the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Professional and services fees (acquisition-related) $ — $ — $ 165 Professional and services fees (disposal-related) — 414 329 Integration-related expenses 4,476 5,872 7,138 $ 4,476 $ 6,286 $ 7,632

SALE OF KANDY COMMUNICATIONS BU

SALE OF KANDY COMMUNICATIONS BUSINESS	12 Months Ended
SALE OF KANDY COMMUNICATIONS BUSINESS	Dec. 31, 2023
Discontinued Operations and Disposal Groups [Abstract]
SALE OF KANDY COMMUNICATIONS BUSINESS	SALE OF KANDY COMMUNICATIONS BUSINESS The Company completed the Kandy Sale on December 1, 2020 (the "Kandy Sale Date"). As consideration, AVCT paid Ribbon $45.0 million, subject to certain adjustments, in the form of Debentures and AVCT Warrants (collectively the "AVCT Units"). The Company received 43,778 AVCT Units as sale consideration. The Debentures bore interest at a rate of 10% per annum, which was added to the principal amount of the Debentures. The Debentures were subject to mandatory conversion if the AVCT stock price was at or above $6.00 per share for 40 trading days in any 60 consecutive trading day period, subject to the satisfaction of certain other conditions. As of February 19, 2021, the stock price had traded above $6.00 for 40 days within a 60 consecutive trading day period, and accordingly, on September 8, 2021 (the "Debenture Conversion Date"), upon the completion of customary regulatory filings by AVCT, the Debentures were converted into 13,700,421 shares of AVCT common stock (the "Debenture Shares"). The AVCT Warrants were independent of the Debentures and entitled the Company to purchase 4,377,800 shares of AVCT common stock at an exercise price of $0.01 per share. The Company calculated the fair value of the Debentures at each measurement date using a Lattice-based valuation approach, which utilizes a binomial tree to model the different paths the price of AVCT's common stock might take over the Debentures' life by using assumptions regarding the stock price volatility and risk-free interest rate. The Company used the Black-Scholes valuation model for estimating the fair value of the AVCT Warrants at each measurement date. The fair value of the AVCT Warrants was affected by AVCT's stock price as well as valuation assumptions, including the volatility of AVCT's stock price, expected term of the option, risk-free interest rate and expected dividends. Both the Lattice and Black-Scholes valuation models are based on available market data, giving consideration to all of the rights and obligations of each instrument and precluding the use of "blockage" discounts or premiums in determining the fair value of a large block of financial instruments. The Company recorded a loss of $74.8 million in the year ended December 31, 2021 arising from the change in the fair value of the AVCT Investment. This loss was included as a component of Other expense net, in the Company's consolidated statements of operations. The Company recorded $3.5 million of interest income in the year ended December 31, 2021, which was added to the principal amount of the Debentures prior to the Debenture Conversion Date, and which is included in Interest expense, net, in the consolidated statement of operations. On August 29, 2022, the Company and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of the Company's investment in the Debenture Shares and the AVCT Warrants with an aggregate fair value of $2.6 million. Pursuant to the settlement agreement, the Company and AVCT also entered into a Wind Down Agreement, pursuant to which a Reseller Agreement between the parties, as previously amended, was terminated, and the Company was granted a non-exclusive perpetual license to use and modify certain intellectual property owned by AVCT comprising WebRTC gateway technology that is integrated with Ribbon’s SBCs and Application Servers. As consideration, the Company paid AVCT $2.5 million in cash, the Debenture Shares were redeemed and canceled, and the AVCT Warrants were terminated and canceled. The perpetual license granted by AVCT is classified as Intangible assets, net in the Company's consolidated balance sheet as of December 31, 2023 and 2022 in the amount of $2.4 million and $3.9 million, respectively. The Company had no investment in AVCT as of December 31, 2023 or 2022 due to the settlement agreement entered into on August 29, 2022. The Company recorded losses of $41.3 million in the year ended December 31, 2022, representing the change in the fair value of the AVCT Investment. The results of the Kandy Communications Business are excluded from the Company's consolidated results for all periods subsequent to the Kandy Sale Date.

EARNINGS (LOSS) PER SHARE

EARNINGS (LOSS) PER SHARE	12 Months Ended
EARNINGS (LOSS) PER SHARE	Dec. 31, 2023
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	EARNINGS (LOSS) PER SHARE Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted average number of shares outstanding during the period. For periods in which the Company reports net income, diluted net income per share is determined by using the weighted average number of common and dilutive common equivalent shares outstanding during the period unless the effect is antidilutive. The shares used to compute loss per share were as follows (in thousands): Year ended December 31, 2023 2022 2021 Weighted average shares outstanding—basic 170,408 156,668 147,575 Potential dilutive common shares — — — Weighted average shares outstanding—diluted 170,408 156,668 147,575 Options to purchase the Company's common stock and unvested restricted and performance-based stock units aggregating 13.5 million shares , 14.5 million shares, and 10.6 million shares were excluded from the computation of diluted loss per share for the years ended December 31, 2023, 2022 and 2021, respectively, because their effect would have been antidilutive. As of December 31, 2023, the potential number of dilutive shares from the Warrants totaled 4.9 million shares. However, there was no impact on weighted average shares outstanding from these Warrants for the year ended December 31, 2023 as the average share price of the Company's common stock was below the exercise price of $3.77 per share and their effect would have been antidilutive. Dividends payable on the Preferred Stock are not an adjustment to net income (loss) used for the calculation of diluted earnings (loss) per share as these dividends are included in the fair value adjustment of the Preferred Stock which is reflected in Other expense, net.

FAIR VALUE HIERARCHY

FAIR VALUE HIERARCHY	12 Months Ended
FAIR VALUE HIERARCHY	Dec. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE HIERARCHY	FAIR VALUE HIERARCHY Fair Value Hierarchy Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The three-tier fair value hierarchy is based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument's categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows: Level 1. Level 1 applies to assets or liabilities for which there are quoted prices in active markets for identical assets or liabilities. The Company had no assets or liabilities fair valued using Level 1 input at December 31, 2023 or 2022. Level 2. Level 2 applies to assets or liabilities for which there are inputs that are directly or indirectly observable in the marketplace, such as quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets). At December 31, 2023, the Company determined the fair value of its defined benefit plans' assets using Level 2 input. At December 31, 2022, the Company determined the fair value of its interest rate swap and its defined benefit plans' assets using Level 2 input. Level 3. Level 3 applies to assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of the assets or liabilities. At December 31, 2023, the fair value of the Company's Preferred Stock and Warrants were determined using Level 3 input. The Company had no assets or liabilities fair valued using Level 3 input at December 31, 2023 or 2022.

ACCOUNTS RECEIVABLE, NET

ACCOUNTS RECEIVABLE, NET	12 Months Ended
ACCOUNTS RECEIVABLE, NET	Dec. 31, 2023
Receivables [Abstract]
ACCOUNTS RECEIVABLE, NET	ACCOUNTS RECEIVABLE, NET Accounts receivable, net, consisted of the following (in thousands): December 31, 2023 2022 Accounts receivable $ 269,933 $ 268,671 Allowance for doubtful accounts (1,512) (1,427) Accounts receivable, net $ 268,421 $ 267,244 The Company's allowance for doubtful accounts activity was as follows (in thousands): Year ended December 31, Balance at Charges Charges (credits) to other accounts Write-offs Balance at 2023 $ 1,427 $ 428 $ 143 $ (486) $ 1,512 2022 $ 1,270 $ 100 $ 159 $ (102) $ 1,427 2021 $ 776 $ 553 $ 85 $ (144) $ 1,270

INVENTORY

INVENTORY	12 Months Ended
INVENTORY	Dec. 31, 2023
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY Inventory consisted of the following (in thousands): December 31, 2023 2022 On-hand final assemblies and finished goods inventories $ 93,077 $ 85,888 Deferred cost of goods sold 3,269 1,449 96,346 87,337 Less noncurrent portion (included in Other assets) (18,825) (11,914) Current portion $ 77,521 $ 75,423

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
PROPERTY AND EQUIPMENT	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment consisted of the following (in thousands): December 31, Useful Life 2023 2022 Equipment 2-5 years $ 77,205 $ 76,674 Software 2-5 years 34,802 33,639 Furniture and fixtures 3-5 years 3,301 3,168 Leasehold improvements Shorter of the estimated lease term or useful life 36,383 35,448 151,691 148,929 Less accumulated depreciation and amortization (109,871) (104,097) Property and equipment, net $ 41,820 $ 44,832 The Company recorded depreciation and amortization expense related to property and equipment of $14.1 million for the year ended December 31, 2023, $15.3 million for the year ended December 31, 2022 and $17.0 million for the year ended December 31, 2021. During each of these years, the Company disposed of certain property and equipment that was fully depreciated at the time of disposal, which resulted in reductions in both Cost and Accumulated depreciation. The net book values of the Company's property and equipment by geographic area were as follows (in thousands): December 31, 2023 2022 United States $ 20,807 $ 23,143 Canada 3,175 3,471 Asia/Pacific 8,314 8,152 Europe 957 833 Israel 8,309 8,860 Other 258 373 $ 41,820 $ 44,832

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL	12 Months Ended
INTANGIBLE ASSETS AND GOODWILL	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND GOODWILL	INTANGIBLE ASSETS AND GOODWILL The Company's intangible assets at December 31, 2023 and 2022 consisted of the following (in thousands): December 31, 2023 Weighted average amortization period Cost Accumulated Net Developed technology 7.84 $ 340,380 $ 239,066 $ 101,314 Customer relationships 11.86 268,140 134,743 133,397 Trade names 3.88 5,000 4,901 99 Software licenses 3.00 5,436 2,159 3,277 9.51 $ 618,956 $ 380,869 $ 238,087 December 31, 2022 Weighted average amortization period Cost Accumulated Net Developed technology 7.84 $ 340,380 $ 212,448 $ 127,932 Customer relationships 11.86 268,140 106,385 161,755 Trade names 3.88 5,000 4,658 342 Software licenses 3.00 5,186 487 4,699 9.51 $ 618,706 $ 323,978 $ 294,728 Estimated future amortization expense for the Company's intangible assets at December 31, 2023 was as follows (in thousands): Years ending December 31, 2024 $ 50,800 2025 44,089 2026 39,039 2027 33,935 2028 23,400 Thereafter 46,824 $ 238,087 Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may be either an operating segment or a portion of an operating segment. The Company's reporting units are its two operating segments, Cloud and Edge and IP Optical Networks. Annual testing for impairment of goodwill is completed as of October 1. Upon completion of the 2023 and 2022 annual tests for goodwill impairment, the Company determined that there was no impairment of goodwill in either of its reporting units. There was no change in the carrying value of the Company's goodwill in the years ended December 31, 2022 and 2023. The components of goodwill at December 31, 2022 and 2023 were as follows (in thousands): Cloud and Edge IP Optical Networks Total Balance at December 31, 2022 Goodwill $ 392,302 $ 191,996 $ 584,298 Accumulated impairment losses (167,406) (116,000) (283,406) 224,896 75,996 300,892 Balance at December 31, 2023 Goodwill $ 392,302 $ 191,996 $ 584,298 Accumulated impairment losses (167,406) (116,000) (283,406) $ 224,896 $ 75,996 $ 300,892

ACCRUED EXPENSES AND OTHER

ACCRUED EXPENSES AND OTHER	12 Months Ended
ACCRUED EXPENSES AND OTHER	Dec. 31, 2023
Payables and Accruals [Abstract]
ACCRUED EXPENSES AND OTHER	ACCRUED EXPENSES AND OTHER Accrued expenses and other consisted of the following (in thousands): December 31, 2023 2022 Employee compensation and related costs $ 33,682 $ 25,994 Professional fees 19,702 17,195 Taxes payable 8,383 8,152 Other 29,920 33,929 $ 91,687 $ 85,270

WARRANTY

WARRANTY	12 Months Ended
WARRANTY	Dec. 31, 2023
Guarantees and Product Warranties [Abstract]
WARRANTY	WARRANTY The changes in the Company's warranty accrual balance in the years ended December 31, 2023 and 2022 were as follows (in thousands): Year ended December 31, Balance at Provision Settlements Balance at 2023 $ 11,857 $ 5,875 $ (5,489) $ 12,243 2022 $ 13,120 $ 4,605 $ (5,868) $ 11,857

RESTRUCTURING AND FACILITIES CO

RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES	12 Months Ended
RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES	RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES The Company recorded restructuring and related expense aggregating $16.2 million, $10.8 million and $11.7 million in the years ended December 31, 2023, 2022 and 2021, respectively. Restructuring and related expense includes restructuring expense (primarily severance and related costs), estimated future variable and other lease costs for vacated properties with no intent or ability of sublease, and accelerated rent amortization expense. For restructuring events that involve lease assets and liabilities, the Company applies lease reassessment and modification guidance and evaluates the right-of-use assets for potential impairment. If the Company plans to exit all or distinct portions of a facility and does not have the ability or intent to sublease, the Company will accelerate the amortization of each of those lease components through the vacate date. The accelerated amortization is recorded as a component of Restructuring and related expense in the Company's consolidated statements of operations. Related variable lease expenses will continue to be expensed as incurred through the vacate date, at which time the Company will reassess the liability balance to ensure it appropriately reflects the remaining liability associated with the premises and record a liability for the estimated future variable lease costs. Accelerated amortization of lease assets is recognized from the date that the Company commences the plan to fully or partially vacate a facility, for which there is no intent or ability to enter into a sublease, through the final vacate date. Amounts of accelerated rent amortization that are included as a component of restructuring and related expense are not included in the tables below, as the liability for the total lease payments for each respective facility is included as a component of Operating lease liabilities in the Company's consolidated balance sheets at December 31, 2023 and 2022, both current and noncurrent (see Note 21). The Company may incur additional future expense if it is unable to sublease other locations included in the Facilities Initiative. The components of restructuring and related expense for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Severance and related costs $ 9,875 $ 5,230 $ 4,618 Variable and other facilities-related costs 5,326 3,992 5,710 Accelerated amortization of lease assets due to cease-use 1,008 1,611 1,325 $ 16,209 $ 10,833 $ 11,653 2023 Restructuring Plan On February 22, 2023, the Company's Board of Directors approved a strategic restructuring program (the "2023 Restructuring Plan") to streamline the Company's operations in order to support the Company's investment in critical growth areas. The 2023 Restructuring Plan includes, among other things, charges related to a workforce reduction. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements. The Company recorded restructuring and related expense of $9.9 million in 2023 in connection with the 2023 Restructuring Plan entirely for severance related costs. A summary of the 2023 Restructuring Plan accrual activity for the year ended December 31, 2023 is as follows (in thousands): Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ — $ 9,875 $ (9,204) $ — $ 671 The Company estimates that it will record nominal future expense under the 2023 Restructuring Plan. 2022 Restructuring Plan On February 14, 2022, the Company's Board of Directors approved a strategic restructuring program (the "2022 Restructuring Plan") to streamline the Company's operations in order to support the Company's investment in critical growth areas. The 2022 Restructuring Plan includes, among other things, charges related to a consolidation of facilities and a workforce reduction. Any positions eliminated in countries outside the United States are subject to local law and consultation requirements. The Company recorded restructuring and related expense of $6.3 million and $10.2 million in connection with the 2022 Restructuring Initiative in the years ended December 31, 2023 and 2022, respectively. The amount for the year ended December 31, 2023 was comprised of $5.3 million for variable and other facilities-related costs and $1.0 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease. The amount for the year ended December 31, 2022 was comprised of $5.3 million for severance and related costs for approximately 70 employees, $3.3 million for variable and other facilities-related costs and $1.6 million for accelerated amortization of lease assets no longer being used with no ability or intent to sublease. The Company estimates that it will record approximately $5 million of expense in 2024 under the 2022 Restructuring Plan. A summary of the 2022 Restructuring Plan accrual activity for the years ended December 31, 2023 and 2022 are as follows (in thousands): Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ 1,164 $ — $ (1,164) $ — $ — Variable and other facilities-related costs 890 5,326 (5,748) — 468 Accelerated amortization of lease assets due to cease-use — 1,008 — (1,008) — $ 2,054 $ 6,334 $ (6,912) $ (1,008) $ 468 Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ — $ 5,287 $ (4,123) $ — $ 1,164 Variable and other facilities-related costs — 3,299 (2,409) — 890 Accelerated amortization of lease assets due to cease-use — 1,611 — (1,611) — $ — $ 10,197 $ (6,532) $ (1,611) $ 2,054 Balance Sheet Classification The current portions of accrued restructuring were $1.1 million and $1.3 million at December 31, 2023 and 2022 , respectively, and are included as components of Accrued expenses in the consolidated balance sheets. The long-term portions of accrued restructuring are included as components of Other long-term liabilities in the consolidated balance sheets. The long-term portions of accrued restructuring were $1.1 million and $2.0 million at December 31, 2023 and 2022 , respectively.

DEBT

DEBT	12 Months Ended
DEBT	Dec. 31, 2023
Debt Disclosure [Abstract]
DEBT	DEBT 2020 Credit Facility On March 3, 2020, the Company entered into a Senior Secured Credit Facilities Credit Agreement (as amended, the "2020 Credit Facility"), by and among the Company, as a guarantor, Ribbon Communications Operating Company, Inc., as the borrower ("Borrower"), Citizens Bank, N.A. ("Citizens"), Santander Bank, N.A., and others as lenders, ("Lenders"). The proceeds of the Credit Agreement were used, in part, to pay off in full all obligations of the Company under the 2019 Credit Facility. The 2020 Credit Facility originally provided for $500 million of commitments from the Lenders to the Borrower, comprised of $400 million in term loans (the "2020 Term Loan Facility") and a $100 million facility available for revolving loans (the "2020 Revolving Credit Facility"). Under the 2020 Revolving Credit Facility, a $30 million sublimit was originally available for letters of credit and a $20 million sublimit is available for swingline loans. The indebtedness and other obligations under the 2020 Credit Facility are unconditionally guaranteed on a senior secured basis by the Company, Edgewater Networks, Inc., a wholly-owned subsidiary of the Company, and GENBAND Inc., wholly-owned subsidiary of the Company (together, the "Guarantors") . The 2020 Credit Facility is secured by first-priority liens on substantially all of the assets of the Borrower and the Guarantors , including substantially all of the assets of the Company. The 2020 Credit Facility requires compliance with certain financial covenants, including a minimum Consolidated Fixed Charge Coverage Ratio and a maximum Consolidated Net Leverage Ratio (each as defined in the 2020 Credit Facility, and each tested on a quarterly basis). On August 18, 2020, the Company entered into the First Amendment to the 2020 Credit Facility in which $75 million of the 2020 Term Loan Facility was assigned from Citizens to a new lender and designated as the Term B Loan. The remaining $325 million of the 2020 Term Loan Facility was deemed the Term A Loan. The Term A Loan and the 2020 Revolving Credit Facility mature in March 2025 and originally bore interest at the Borrower's option at either the LIBOR rate plus a margin ranging from 1.50% to 3.50% per year, or the base rate plus 0.50%, or the prime rate plus a margin ranging from 0.50% to 2.50% per year (the "Applicable Margin"). The Applicable Margin varied depending on the Company's Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility). The Term B Loan was scheduled to mature in March 2026 and bore interest, at the Borrower's option, at either the LIBOR rate plus a margin of 7.50% per year, or the base rate (the highest of the Federal Funds Effective Rate (as defined in the First Amendment) plus 0.50%, or the prime rate. On December 1, 2020, the Company entered into the Second Amendment to the 2020 Credit Facility to obtain consent for an equity exchange with AVCT in connection with the sale of our Kandy Communications business, as well as to amend certain other provisions of the 2020 Credit Facility. On March 3, 2021, the Company entered into the Third Amendment to the 2020 Credit Facility which provided for an incremental term loan facility in the principal amount of $74.6 million, the proceeds of which were used to consummate an open market purchase of all outstanding amounts under the Term B Loan, resulting in the assignment and immediate cancellation of the Term B Loan, such that the outstanding amount under the Term A Loan and incremental term loan facility were combined and held by the Lenders (the "2020 Term Loan") with the same terms as the Term A Loan. The Company wrote off $2.5 million of capitalized debt issuance costs in connection with the Third Amendment, which is included in Interest expense, net, in the Company's consolidated statement of operations for the year ended December 31, 2021. On March 10, 2022, the Company entered into the Fourth Amendment to the 2020 Credit Facility to increase the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility) and in conjunction, the Company made a $15.0 million prepayment that was applied to the final payment due on the maturity date. On June 30, 2022, the Company entered into the Fifth Amendment to the 2020 Credit Facility (the "Fifth Amendment") to increase the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility) for 2022, with the fourth quarter of 2022 increased to 4.75:1.00, the first and second quarters of 2023 declining to 3.25:1.00, and in all subsequent quarters the ratio was to be fixed at 3.00:1.00. Also, the Fifth Amendment reduced the minimum Consolidated Fixed Charge Coverage Ratio (as defined in the 2020 Credit Facility) in 2022, with the fourth quarter of 2022 reduced to 1.10:1.00 and in all subsequent quarters the ratio was to be fixed at 1.25:1.00. In addition, the Fifth Amendment increased the maximum rate at which loans were to bear interest if the Company's Consolidated Net Leverage Ratio for any quarter was greater than 4.50:1.00. Specifically, loans incurred were to bear interest, at the Borrower’s option, at either LIBOR plus a margin ranging from 1.50% to 4.50% per year, or the base rate plus 0.50%, or the prime rate plus a margin ranging from 0.50% to 3.50% per year. The Fifth Amendment also allowed the Company to incur junior secured or unsecured debt in an amount no less than $50 million, subject to certain conditions, including the requirement that 50% of the aggregate amount of such incurred debt (net of certain costs, fees and other amounts) must be applied to prepay the 2020 Credit Facility, and compliance with certain leverage ratio-based covenant exceptions. In connection with the Fifth Amendment, the Company made a $10.0 million voluntary prepayment that was applied to the final payment due on the maturity date. Subsequent to the Fifth Amendment, the Company is required to make quarterly principal payments on the 2020 Term Loan aggregating approximately $5.0 million per quarter through March 31, 2024 and $10.0 million in each of the three quarters thereafter, with the remaining and final payment due on the maturity date in March 2025. On March 24, 2023, the Company entered into the Sixth Amendment to the 2020 Credit Facility (the “Sixth Amendment”) effective March 30, 2023. The Sixth Amendment, among other things, increased the Maximum Consolidated Net Leverage Ratio (as defined in the 2020 Credit Facility), with the first, second and third quarters of 2023 increasing to 4.50:1.00 and then decreasing to 4.25:1.00 and 4.00:1.00 in the fourth quarter of 2023 and the first quarter of 2024, respectively. In all subsequent quarters, the Maximum Consolidated Senior Net Leverage Ratio will be fixed at 3.00:1.00 and the Maximum Consolidated Net Leverage Ratio will be fixed at 4.00:1.00 . Also, the Sixth Amendment reduced the minimum Consolidated Fixed Charge Coverage Ratio (as defined in the 2020 Credit Facility) to 1.10:1.00 through the first quarter of 2024 and in all subsequent quarters the ratio will be fixed at 1.25:1.00. The Sixth Amendment reduced the maximum borrowings allowed under the 2020 Revolving Credit Facility from $100 million to $75 million and the sublimit available for letters of credit was reduced from $30 million to $20 million. In addition, the Sixth Amendment replaced LIBOR with the Secured Overnight Financing Rate ("SOFR") as the alternative rate that may be used by the Company for calculating interest owed under the 2020 Credit Facility, with the margin now fixed at 4.5%. In conjunction with the Sixth Amendment, the Company made a $75 million prepayment that was applied to the final payment due upon maturity in March 2025 of approximately $200.3 million. The $75 million prepayment was almost entirely funded with the net proceeds from the Private Placement and the sales of our interest rate swap. Debt issuance costs associated with the Sixth Amendment totaled $1.7 million and are being amortized on a straight-line basis over the remaining life of the 2020 Credit Facility to Interest expense, net. The Company's interest rates under the 2020 Term Loan b enefited from a hedge instrument that was in place, specifically a fixed rate swap, until the instrument was sold in March 2023 (see Note 15). As a result of the sale of the fixed rate swap, the ongoing interest rate is now based upon U.S. dollar SOFR, plus a fixed margin of 4.5%. The Company was in compliance with all covenants of the 2020 Credit Facility at both December 31, 2023 and 2022, including the current Consolidated Net Leverage Ratio calculation that considers the Company's debt to include Preferred Stock. The Company had the following outstanding borrowings, unamortized debt issuance costs, letters of credit, interest rates, and remaining borrowing capacity under the 2020 Credit Facility as of December 31, 2023 and 2022, respectively: December 31, December 31, Current portion of Term Debt $ 35,102 $ 20,058 Long-term Debt, net of Current: Long-term Debt, net of Current (Face Amount) $ 200,293 $ 310,395 Unamortized Debt Issuance Costs - Contra-Liability (2,811) (4,125) Long-term Debt, net of Current $ 197,482 $ 306,270 Total Face Amount of Borrowings $ 235,395 $ 330,453 Unamortized Debt Issuance Costs: Other Assets $ 557 $ 798 Long-Term Debt - Contra Liability 2,811 4,125 Total Unamortized Debt Issuance Costs $ 3,368 $ 4,923 Letters of Credit Outstanding $ 2,711 $ 3,272 Remaining Borrowing Capacity $ 72,289 $ 96,728 Average Interest Rates: Term Loan 10.0 % 5.4 % Letters of Credit 4.5 % 4.5 % The Company's debt maturities as of December 31, 2023 were as follows: Years ending December 31, 2024 35,102 2025 200,293 235,395 Letters of Credit and Performance and Bid Bonds The Company uses letters of credit, bank guarantees, and performance and bid bonds in the course of its business. At December 31, 2023, the Company had $7.9 million of letters of credit, bank guarantees, and performance and bid bonds outstanding (collectively, "Guarantees"), comprised of the $2.7 million of letters of credit under the 2020 Credit Facility described above (the "Letters of Credit") and $5.2 million of bank guarantees and performance and bid bonds (collectively, the "Other Guarantees") under various uncommitted facilities. At December 31, 2022, the Company had Guarantees aggregating $8.3 million, comprised of the $3.3 million of Letters of Credit and $5.0 million of Other Guarantees.

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	12 Months Ended
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES The Company is exposed to financial market risk related to foreign currency fluctuations and changes in interest rates. These exposures are actively monitored by management. To manage the volatility related to the exposure to changes in interest rates, the Company may enter into derivative financial instruments. Management's objective has been to reduce, where it is deemed appropriate to do so, fluctuations in earnings and cash flows associated with changes in interest rates. Ribbon's policies and practices are to use derivative financial instruments only to the extent necessary to manage exposures. Ribbon does not hold or issue derivative financial instruments for trading or speculative purposes. The Company records derivatives on the balance sheet at fair value. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative, whether the Company has elected to designate a derivative in a hedging relationship and apply hedge accounting and whether the hedging relationship has satisfied the criteria necessary to apply hedge accounting. Derivatives designated and qualifying as a hedge of the exposure to changes in the fair value of an asset, liability, or firm commitment attributable to a specific risk, such as interest rate risk, are considered fair value hedges. Derivatives designated and qualifying as a hedge of the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Derivatives may also be designated as hedges of the foreign currency exposure of a net investment in a foreign operation. Hedge accounting generally provides for the matching of the timing of gain or loss recognition on the hedging instrument with the recognition of the changes in the fair value of the hedged asset or liability that are attributable to the hedged risk in a fair value hedge, or the earnings effect of the hedged forecasted transactions in a cash flow hedge. The Company may enter into derivative contracts that are intended to economically hedge certain of its risk even though hedge accounting does not apply or the Company elects not to apply hedge accounting. Cash Flow Hedge of Interest Rate Risk The 2020 Term Loan Facility had outstanding balances of $235.4 million and $330.4 million at December 31, 2023 and 2022 , respectively. The 2020 Revolving Credit Facility was undrawn at both December 31, 2023 and 2022 . Borrowings under the 2020 Credit Facility have variable interest rates based on LIBOR or SOFR (see Note 14). As a result of exposure to interest rate movements, during March 2020, the Company entered into an interest rate swap arrangement, which effectively converted its $400 million term loan with its variable interest rate based upon one-month LIBOR to an aggregate fixed rate of 0.904%, plus a leverage-based margin as defined in the 2020 Credit Facility. On July 22, 2022, the Company sold $30 million of the notional amount of its interest rate swap back to its counterparty for $1.5 million, reducing the notional amount of this swap to $370 million. On August 16, 2022 the Company sold another $30 million of the notional amount of its interest rate swap back to its counterparty for $1.6 million, reducing the notional amount to $340 million, which approximated the current level of our term loan debt then outstanding. The gain in Accumulated other comprehensive income related to the $60 million notional amount sold of $3.1 million is being released into earnings on a straight-line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense, the amortization of which totaled $0.9 million and $0.5 million for the years ended December 31, 2023 and 2022. On March 24 , 2023, the Company received $9.4 million, consisting of $0.4 million of interest and $9.0 million for the sale of $170 million of its $340 million notional amount interest rate swap back to its counterparty, reducing the notional amount to $170 million. On March 27 , 2023, the Company received $9.8 million, consisting of $0.4 million of interest and $9.4 million for the sale of the remaining $170 million of its interest rate swap back to its counterparty. The portion of the gain in Accumulated other comprehensive income related to the term loan debt prepaid on the date of the final sale of our swap totaled $7.3 million and was released into earnings immediately as Other expense, net. The portion of the gain in Accumulated other comprehensive income related to our remaining term loan debt balance was $12.0 million and is being released into earnings on a straight-line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense, the amortization of which totaled $4.7 million for the year ended December 31, 2023. The Company’s objectives in using interest rate derivatives have been to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company has used an interest rate swap as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. The effective portion of changes in the fair value of designated derivatives that qualify as cash flow hedges is recorded in Accumulated other comprehensive income in the consolidated balance sheet and is subsequently reclassified into earnings in the period that the hedged forecasted transactions affect earnings. During the years ended December 31, 2023 and 2022 , such a derivative was used to hedge the variable cash flows associated with the credit facilities under the 2020 Credit Facility, and the Company has accounted for this derivative as an effective hedge until the final portion of the swap was sold on March 27, 2023. Any ineffective portion of the change in the fair value of the derivative was recognized directly in earnings. Amounts reported in Accumulated other comprehensive income related to the Company's derivative are reclassified to interest expense as interest is accrued on the Company’s variable-rate debt. The impact of the Company’s derivative financial instrument on its consolidated statement of comprehensive (loss) income for the years ended December 31, 2023 and 2022 was as follows, net of tax (in thousands): Year ended December 31, 2023 2022 Gain (loss) recognized in other comprehensive income (loss) on swap, net of tax $ (2,715) $ 22,456 Amount reclassified from accumulated other comprehensive income to other expense, net upon sale of swap, net of tax (5,099) — Amount reclassified from accumulated other comprehensive income to interest expense (7,300) (3,135) Unrealized gain (loss) on interest rate swap, net of reclassifications and amortization $ (15,114) $ 19,321 The Company had no derivative assets or liabilities at December 31, 2023. The fair values and locations in the consolidated balance sheet at December 31, 2022 of the Company's derivative assets (liabilities) designated as a hedging instrument were as follows (in thousands): Balance sheet location December 31, 2022 Interest rate derivative - asset derivative Other current assets $ 13,212 Interest rate derivative - asset derivative Other assets 12,216 $ 25,428 The Company classified its interest rate derivative aggregating $25.4 million at December 31, 2022 , as Level 2 fair value measurements within the fair value hierarchy (see Note 6).

PREFERRED STOCK AND WARRANTS

PREFERRED STOCK AND WARRANTS	12 Months Ended
PREFERRED STOCK AND WARRANTS	Dec. 31, 2023
Equity [Abstract]
PREFERRED STOCK AND WARRANTS	PREFERRED STOCK AND WARRANTS On March 28, 2023, the Company issued 55,000 shares of Preferred Stock to investors in the Private Placement at a price of $970 per share, along with 4,858,090 Warrants with an exercise price of $3.77 per share. The Company accounts for the Preferred Stock and Warrants as liability-classified instruments based on an assessment of their specific terms in accordance with ASC Topic 480, Distinguishing Liabilities from Equity . The fair value option was elected for the Preferred Stock, as the Company considers fair value to best reflect its expected future economic value. These liabilities are remeasured to fair value at each reporting date using the same valuation methodology applied upon issuance using current input assumptions. The value of the Preferred Stock is calculated using the Black-Derman-Toy (BDT) stochastic yield lattice model to capture the optimal timing of repayment, increasing dividend rate and other features and the value of the Warrants is calculated using the Black-Scholes Pricing Model. Changes in the fair value of the Preferred Stock and Warrants are reported as Other expense, net in the Company's consolidated statements of operations. The Company determined the fair value of the Preferred Stock and Warrants using Level 3 input. The key assumptions input into the models utilized were as follows as of December 31, 2023: Preferred Stock (BDT) Face value per share $1,000 Interest payments per year 4 Dividend rate - year 1 (paid in-kind) 9.25% Dividend rate - year 2 (paid in-kind or in cash at the Company's choice) 9.75% Dividend rate - thereafter (paid in cash) 12.00% Yield volatility 25.0% Time to maturity (in years) 1.8 Warrants (Black-Scholes) Stock price $2.90 Strike price $3.77 Risk-free rate 3.95% Volatility 60.5% Dividend yield 0.0% Time to expiration (years) 3.2 The changes in the Company's Preferred Stock and Warrant liabilities for the year ended December 31, 2023 were as follows (in thousands): Preferred stock liability Balance at January 1, 2023 $ — Issued 47,854 Cumulative dividends 3,935 Fair value change 1,548 Balance at December 31,2023 $ 53,337 Warrant liability Balance at January 1, 2023 $ — Issued 5,496 Fair value change (201) Balance at December 31,2023 $ 5,295 The Preferred Stock is subordinate to Company indebtedness and senior to the Company’s common stock or other equity. Holders of the Preferred Stock are entitled to cumulative dividends that accrue quarterly through the September 30, 2025 maturity date. Dividends are payable in-kind during the first year at a rate of 9.25%. At the Company’s option, the dividends are payable in-kind or in cash during the second year at a rate of 9.75%. Dividends thereafter are payable in cash at a rate of 12.00%. The proceeds from the Preferred Stock issuance were approximately $53.4 million, including $10.0 million from existing related party stockholders. Offering costs paid by the Company of approximately $3.5 million were recorded in Other expense, net in the year ended December 31, 2023. The net proceeds from the Private Placement were used for the repayment of debt. The Preferred Stock is redeemable on or after the first and second anniversaries of the closing date at a rate of 103% and 102%, respectively. The Warrants are immediately exercisable and upon an event such as a merger, consolidation, asset sale or similar change of control, the Warrants may be exercised and the holders may vote the underlying shares of common stock. In connection with the Private Placement, the Company provided the investors with certain registration rights relating to the Preferred Stock, the Warrants and the shares of the Company’s common stock underlying the Warrants, that required the Company to file a registration statement on Form S-3 with the SEC within 30 days following the closing date of the Private Placement. The registration requirement was completed on May 19, 2023.

REVENUE RECOGNITION

REVENUE RECOGNITION	12 Months Ended
REVENUE RECOGNITION	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION The Company's typical performance obligations include the following: Performance Obligation When Performance Obligation is Typically Satisfied When Payment is Typically Due Software and Product Revenue Software licenses (perpetual or term) Upon transfer of control; typically, when made available for download (point in time) Generally, within 30 days of invoicing except for term licenses, which may be paid for over time Software licenses (subscription) Upon activation of hosted site (over time) Generally, within 30 days of invoicing Hardware When control of the hardware passes to the customer; typically, upon delivery (point in time) Generally, within 30 days of invoicing Software upgrades Upon transfer of control; typically, when made available for download (point in time) Generally, within 30 days of invoicing Customer Support Revenue Customer support Ratably over the course of the support contract (over time) Generally, within 30 days of invoicing Professional Services Other professional services (excluding training services) As work is performed (over time) Generally, within 30 days of invoicing (upon completion of services) Training When the class is taught (point in time) Generally, within 30 days of services being performed Significant Judgments The Company's contracts with customers often include promises to transfer multiple products and services to the customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. Judgment is required to determine the standalone selling price for each distinct performance obligation. The Company typically has more than one standalone selling price ("SSP") for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, the Company may use information such as the size of the customer and geographic region in determining the SSP. Deferred Revenue Deferred revenue is a contract liability representing amounts collected from or invoiced to customers in excess of revenue recognized. This results primarily from the billing of annual customer support agreements where the revenue is recognized over the term of the agreement. The value of deferred revenue will increase or decrease based on the timing of invoices and recognition of revenue. Disaggregation of Revenue The Company disaggregates its revenue from contracts with customers based on the nature of the products and services and the geographic regions in which each customer is domiciled. The Company's total revenue for the years ended December 31, 2023, 2022 and 2021 was disaggregated geographically as follows: Year ended December 31, 2023 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 161,945 $ 133,737 $ 48,733 $ 344,415 Europe, Middle East and Africa 151,938 75,478 34,485 261,901 Asia Pacific 115,923 39,891 11,269 167,083 Other 15,344 30,546 7,050 52,940 $ 445,150 $ 279,652 $ 101,537 $ 826,339 Year ended December 31, 2022 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 175,189 $ 132,655 $ 44,819 $ 352,663 Europe, Middle East and Africa 147,523 75,948 29,310 252,781 Asia Pacific 95,828 41,677 13,594 151,099 Other 24,140 31,815 7,262 63,217 $ 442,680 $ 282,095 $ 94,985 $ 819,760 Year ended December 31, 2021 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 196,058 $ 132,683 $ 47,296 $ 376,037 Europe, Middle East and Africa 138,203 79,475 30,349 248,027 Asia Pacific 92,803 41,945 18,183 152,931 Other 25,978 32,218 9,766 67,962 $ 453,042 $ 286,321 $ 105,594 $ 844,957 The Company's product revenue from its direct sales program and from indirect sales through its channel partner program for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Indirect sales through channel program $ 157,495 $ 131,998 $ 117,065 Direct sales 287,655 310,682 335,977 $ 445,150 $ 442,680 $ 453,042 The Company's product revenue from sales to enterprise customers and from sales to service provider customers for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Sales to enterprise customers $ 143,853 $ 125,664 $ 111,494 Sales to service provider customers 301,297 317,016 341,548 $ 445,150 $ 442,680 $ 453,042 The Company's product revenue and service revenue components by segment for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Product revenue Cloud and Edge 184,730 215,770 248,570 IP Optical Networks 260,420 226,910 204,472 Total product revenue 445,150 442,680 453,042 Service revenue Maintenance Cloud and Edge 219,939 222,238 228,321 IP Optical Networks 59,713 59,857 58,000 Total maintenance revenue 279,652 282,095 286,321 Professional services Cloud and Edge 72,979 70,130 79,765 IP Optical Networks 28,558 24,855 25,829 Total professional services revenue 101,537 94,985 105,594 Total service revenue 381,189 377,080 391,915 Revenue Contract Balances The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables, which are contract assets, and customer advances and deposits, which are contract liabilities, in the Company's consolidated balance sheets. Amounts are billed as work progresses in accordance with agreed-upon contractual terms, either at periodic intervals or upon achievement of contractual milestones. Completion of services and billing may occur subsequent to revenue recognition, resulting in contract assets. The Company may receive advances or deposits from its customers before revenue is recognized, resulting in contract liabilities which are classified as deferred revenue. These assets and liabilities are reported in the Company's consolidated balance sheets on a contract-by-contract basis as of the end of each reporting period. Changes in the contract asset and liability balances during the years ended December 31, 2023 and 2022 were not materially impacted by any factors other than billing and revenue recognition. Nearly all of the Company's deferred revenue balance is related to services revenue, primarily customer support contracts. Unbilled receivables stem primarily from engagements where services have been performed; however, billing cannot occur until services are completed. In some arrangements, the Company allows customers to pay for term-based software licenses and products over the term of the software license. The Company also sells SaaS-based software under subscription arrangements, with payment terms over the term of the SaaS agreement. Amounts recognized as revenue in excess of amounts billed are recorded as unbilled receivables. Unbilled receivables that are anticipated to be invoiced in the next twelve months are included in Accounts receivable on the Company's consolidated balance sheets. The changes in the Company's accounts receivable, unbilled receivables and deferred revenue balances for the years ended December 31, 2023 and 2022 were as follows (in thousands): Accounts receivable Unbilled accounts receivable Deferred revenue (current) Deferred revenue (long-term) Balance at January 1, 2023 $ 170,969 $ 96,275 $ 113,939 $ 19,254 Increase (decrease), net 15,969 (14,792) (558) (36) Balance at December 31, 2023 $ 186,938 $ 81,483 $ 113,381 $ 19,218 Accounts receivable Unbilled accounts receivable Deferred revenue (current) Deferred revenue (long-term) Balance at January 1, 2022 $ 208,972 $ 73,945 $ 109,119 $ 20,619 Increase (decrease), net (38,003) 22,330 4,820 (1,365) Balance at December 31, 2022 $ 170,969 $ 96,275 $ 113,939 $ 19,254 The Company recognized approximately $108 million of revenue in the year ended December 31, 2023 that was recorded as deferred revenue at December 31, 2022 and approximately $103 million of revenue in the year ended December 31, 2022 that was recorded as deferred revenue at December 31, 2021. Of the Company's deferred revenue reported as long-term in its consolidated balance sheet at December 31, 2023, the Company expects that approximately $13 million will be recognized as revenue in 2025, approximately $4 million will be recognized as revenue in 2026 and approximately $2 million will be recognized as revenue in 2027 and beyond. All freight-related customer invoicing is recorded as revenue, while the shipping and handling costs that occur after control of the promised goods or services transfer to the customer are reported as fulfillment costs, a component of Cost of revenue - product in the Company's consolidated statements of operations. Deferred Commissions Cost Sales commissions earned by the Company's employees are considered incremental and recoverable costs of obtaining a contract with a customer. The payments related to these costs have been deferred on our consolidated balance sheet and are being amortized over the expected life of the customer contract, which is generally five years. At December 31, 2023 and 2022 , the Company had $3.0 million and $3.6 million, respectively, of deferred sales commissions capitalized.

OPERATING SEGMENT INFORMATION

OPERATING SEGMENT INFORMATION	12 Months Ended
OPERATING SEGMENT INFORMATION	Dec. 31, 2023
Segment Reporting [Abstract]
OPERATING SEGMENT INFORMATION	OPERATING SEGMENT INFORMATION The Company has two reportable segments, which are intended to align with the manner in which the business is managed: Cloud and Edge, and IP Optical Networks. The Cloud and Edge segment provides secure and reliable software and hardware products, solutions and services for enabling Voice over Internet Protocol ("VoIP") communications, Voice over Long-Term Evolution ("VoLTE") and Voice Over 5G ("VoNR") communications and Unified Communications and Collaboration ("UC&C") within service provider and enterprise networks and from the cloud. The Cloud and Edge products are increasingly software-centric and cloud-native for deployment on private, public or hybrid cloud infrastructures, in data centers, on enterprise premises and within service provider networks. Ribbon's Cloud and Edge product portfolio consists of our Session Border Controller ("SBC") products and our Network Transformation products. The IP Optical Networks segment provides high-performance, secure solutions for IP networking and optical transport, supporting wireless networks including 5G, metro and edge aggregation, core networking, data center interconnect, legacy network transformation and transport solutions for wholesale carriers. This portfolio is offered to service provider, enterprise and industry verticals with critical transport network infrastructures including utilities, government, defense, transportation, and education and research. The Company has not provided segment asset information as such information is not provided to the CODM and accordingly, asset information is not used in assessing segment performance. Segment revenue and expense included in the tables below represent direct revenue and expense attributable to each segment. Please see Note 10 for information regarding the allocation of goodwill between segments. The CODM utilizes revenue and adjusted gross profit to measure and assess each segment's performance. The Company calculates adjusted gross profit by excluding from cost of revenue: amortization of acquired technology, stock-based compensation, acquisition-related inventory adjustments and acquisition-related facilities adjustments, and may also exclude other items in future periods that the Company believes are not part of the Company's core business. Adjusted gross profit is not a financial measure determined in accordance with U.S. GAAP, may not be comparable to similarly titled measures used by other companies, and should not be considered a substitute for gross profit or other results reported in accordance with U.S. GAAP. See below for a reconciliation of adjusted gross profit to gross profit which is the most directly comparable U.S. GAAP measure. The tables below provide revenue, adjusted gross profit and depreciation expense by reportable segment for the years ended December 31, 2023, 2022 and 2021 (in thousands): Year ended December 31, Revenue 2023 2022 2021 Segment revenue: Cloud and Edge $ 477,647 $ 508,137 $ 556,656 IP Optical Networks 348,692 311,623 288,301 Total revenue $ 826,339 $ 819,760 $ 844,957 Year ended December 31, Adjusted gross profit 2023 2022 2021 Segment adjusted gross profit: Cloud and Edge $ 314,594 $ 330,395 $ 370,504 IP Optical Networks 124,436 104,711 114,496 Total segment adjusted gross profit 439,030 435,106 485,000 Stock-based compensation expense (2,657) (2,628) (1,997) Amortization of acquired technology (28,290) (31,542) (38,343) Gross profit $ 408,083 $ 400,936 $ 444,660 Year ended December 31, Depreciation expense 2023 2022 2021 Segment depreciation expense: Cloud and Edge $ 9,798 $ 10,758 $ 12,269 IP Optical Networks 4,307 4,537 4,693 Total depreciation expense $ 14,105 $ 15,295 $ 16,962

MAJOR CUSTOMERS

MAJOR CUSTOMERS	12 Months Ended
MAJOR CUSTOMERS	Dec. 31, 2023
Risks and Uncertainties [Abstract]
MAJOR CUSTOMERS	MAJOR CUSTOMERS The following customers contributed 10% or more of the Company's revenue in at least one of the years ended December 31, 2023, 2022 and 2021: Year ended December 31, 2023 2022 2021 Verizon Communications Inc. 11% 15% 16% At December 31, 2023 and 2022, no customer accounted for 10% or more of the Company's accounts receivable balance. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. The Company maintains an allowance for doubtful accounts and such losses have historically been within management's expectations.

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS	12 Months Ended
STOCK-BASED COMPENSATION PLANS	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION PLANS	STOCK-BASED COMPENSATION PLANS The Company grants stock-based compensation to employees, officers and non-employee directors, as well as consultants and advisors of the Company and its subsidiaries under its Amended and Restated 2019 Incentive Award Plan which provides for the award of stock options, stock appreciation rights, restricted stock awards ("RSAs"), performance-based stock awards, restricted stock units ("RSUs"), performance-based stock units ("PSUs") and other stock- or cash-based awards. Executive Equity Arrangements Inducement Awards In connection with his appointment as President and Chief Executive Officer of Ribbon on March 16, 2020, the Company awarded Bruce McClelland sign-on equity grants, comprised of RSUs and a PSU grant with both market and service conditions. The Company estimates as of December 31, 2023 that the market conditions surrounding the PSUs granted will not be met by the expiration date of September 1, 2024. Performance-Based Stock Grants In addition to granting RSAs and RSUs to its executives and certain of its employees, the Company also grants PSUs to certain of its executives and certain other employees. Vesting periods for RSAs, RSUs, and PSUs granted range from one Restricted Stock Units The activity related to the Company's RSUs for the year ended December 31, 2023 was as follows: Shares Weighted Unvested balance at January 1, 2023 7,649,747 $ 3.96 Granted 4,991,829 $ 2.88 Vested (4,840,738) $ 3.99 Forfeited (709,470) $ 3.97 Unvested balance at December 31, 2023 7,091,368 $ 3.18 The total grant date fair value of restricted stock underlying RSUs that vested was $19.3 million in the year ended December 31, 2023, $18.1 million in the year ended December 31, 2022 and $12.5 million in the year ended December 31, 2021. Performance-Based Stock Units The activity related to the Company's PSUs for the year ended December 31, 2023 was as follows: Shares Weighted Unvested balance at January 1, 2023 6,653,503 $ 2.52 Granted 1,800,202 $ 3.26 Vested (381,071) $ 6.91 Forfeited (1,774,703) $ 4.05 Unvested balance at December 31, 2023 6,297,931 $ 2.07 The total grant date fair value of restricted stock underlying PSUs that vested was $2.6 million in the year ended December 31, 2023, $0.9 million in the year ended December 31, 2022 and $1.7 million in the year ended December 31, 2021. Stock-Based Compensation The consolidated statements of operations included stock-based compensation for the years ended December 31, 2023, 2022 and 2021 as follows (in thousands): Year ended December 31, 2023 2022 2021 Product cost of revenue $ 510 $ 471 $ 313 Service cost of revenue 2,147 2,157 1,684 Research and development 4,933 5,108 4,253 Sales and marketing 7,111 6,074 7,218 General and administrative 7,105 4,897 5,950 $ 21,806 $ 18,707 $ 19,418 At December 31, 2023, there was $17.9 million

LEASES

LEASES	12 Months Ended
LEASES	Dec. 31, 2023
Leases [Abstract]
LEASES	LEASES The Company has operating leases for corporate offices and research and development facilities, and has historically had finance leases for certain equipment. Operating leases are reported separately in the Company's consolidated balance sheets. Assets acquired under finance leases, if any, are included in Property and equipment, net, in the consolidated balance sheets. The Company determines if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides the Company with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, the Company does not separate lease and non-lease components but rather, accounts for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. Right-of-use assets and lease liabilities are initially measured based on the present value of the future minimum fixed lease payments (i.e., fixed payments in the lease contract) over the lease term at the commencement date. As the Company's existing leases do not have a readily determinable implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of future minimum fixed lease payments. The Company calculates its incremental borrowing rate to reflect the interest rate that it would have to pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment over a similar term and considers its historical borrowing activities and market data from entities with comparable credit ratings in this determination. The measurement of the right-of-use asset also includes any lease payments made prior to the commencement date (excluding any lease incentives) and initial direct costs incurred. The Company assessed its right-of-use assets for impairment as of December 31, 2023 and 2022 and determined no impairment has occurred. Lease terms may include options to extend or terminate the lease and the Company incorporates such options in the lease term when it has the unilateral right to make such an election and it is reasonably certain that the Company will exercise that option. In making this determination, the Company considers its prior renewal and termination history and planned usage of the assets under lease, incorporating expected market conditions. For operating leases, lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases includes both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. The Company expenses all variable lease costs as incurred. Certain leased facilities are being partially or fully vacated as part of the 2022 Restructuring Plan and for some of those facilities, the Company has no plans to enter into sublease agreements. Accordingly, the Company accelerated the amortization of those lease assets through the planned cease-use date of each facility, resulting in additional amortization expense of $1.0 million and $1.6 million in the years ended December 31, 2023 and 2022, respectively. No variable lease costs were accrued in the year ended December 31, 2023 for future estimated variable expenses related to assets partially or fully vacated with no intent or ability to sublease. Variable lease costs for the year ended December 31, 2022 included accruals of $1.0 million for all estimated future variable lease costs related to those facilities. The Company did not record any accelerated amortization or estimated future variable lease costs in the year ended December 31, 2023 or 2022 related to the 2020 Restructuring Plan. The Company accelerated amortization totaling $0.8 million in the year ended December 31, 2021 for certain leased facilities that were vacated in 2021 as part of the consolidation of certain sites following the ECI Acquisition. The Company did not record estimated future variable lease costs in the year ended December 31, 2021 related to the 2020 Restructuring Plan. In connection with the 2019 Restructuring Initiative, certain leased facilities were partially or fully vacated as the Company consolidated its facilities, with no plans to enter into sublease agreements for certain of those facilities. The Company did not accelerate amortization or record liabilities for future estimated variable lease costs in the years ended December 31, 2023 or 2022. In the year ended December 31, 2021, the Company accelerated amortization of $3.4 million for certain leased facilities that were vacated in those years and recorded liabilities aggregating $1.4 million for all future estimated variable lease costs related to those facilities. All incremental accelerated amortization and accrual for all estimated future variable lease costs are included in Restructuring and related expense in the Company's consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021. At December 31, 2023 and 2022 , the Company had accruals of $1.5 million and $2.0 million, respectively, for all future anticipated variable lease costs related to these facilities. The Company may incur additional future expense if it is unable to sublease other locations included in the Facilities Initiative. In addition, in the year ended December 31, 2021, this accelerated amortization and provision for future estimated variable lease costs was partially offset by the recognition of $2.1 million of income in conjunction with lease amendments that modified the Company's obligation and rentable square footage at a site in North Carolina. The Company leases its corporate offices and other facilities under operating leases, which expire at various times through 2033. The Company's right-of-use lease assets and lease liabilities at December 31, 2023 and 2022 were as follows (in thousands): December 31, Classification 2023 2022 Assets: Operating lease assets Operating lease right-of-use assets $ 39,783 $ 44,888 Liabilities: Current Operating Operating lease liabilities $ 15,739 $ 15,416 Non-Current Operating Operating lease liabilities, net of current 38,711 46,183 Total lease liabilities $ 54,450 $ 61,599 The components of lease expense for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Operating lease cost* $ 18,767 $ 21,121 $ 21,828 Finance lease cost: Amortization of leased assets — 287 695 Interest on lease liabilities — 13 67 Short-term lease cost 13,978 14,209 13,250 Variable lease costs (costs excluded from minimum fixed lease payments)** 3,364 4,007 4,030 Sublease income (1,376) (1,647) (1,496) Net lease cost $ 34,733 $ 37,990 $ 38,374 * Operating lease costs for the years ended December 31, 2023, 2022 and 2021 include $1.0 million, $1.6 million, and $3.4 million, respectively, of accelerated amortization for certain assets partially or fully vacated with no intent or ability to sublease. Operating lease cost ** Variable lease costs for the years ended December 31, 2022 and 2021 included accruals of $1.0 million and $1.4 million, respectively, for all future estimated variable expenses related to certain assets partially or fully vacated with no intent or ability to sublease. No such variable costs were accrued in the year ended December 31, 2023. Cash flow information related to the Company's leases for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 19,021 $ 20,363 22,365 Operating cash flows from finance leases $ — $ 13 67 Financing cash flows from finance leases $ — $ 595 903 Other information related to the Company's leases as of December 31, 2023 and 2022 was as follows (in thousands): December 31, 2023 2022 Weighted average remaining lease term (years): Operating leases 5.50 5.90 Weighted average discount rate: Operating leases 6.34 % 5.79 % Future minimum fixed lease payments under noncancelable leases at December 31, 2023 were as follows (in thousands): Operating leases 2024 $ 18,542 2025 10,506 2026 8,676 2027 7,569 2028 6,305 2029 and beyond 13,181 Total lease payments 64,779 Less: interest (10,329) Present value of lease liabilities $ 54,450
LEASES	LEASES The Company has operating leases for corporate offices and research and development facilities, and has historically had finance leases for certain equipment. Operating leases are reported separately in the Company's consolidated balance sheets. Assets acquired under finance leases, if any, are included in Property and equipment, net, in the consolidated balance sheets. The Company determines if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides the Company with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, the Company does not separate lease and non-lease components but rather, accounts for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. Right-of-use assets and lease liabilities are initially measured based on the present value of the future minimum fixed lease payments (i.e., fixed payments in the lease contract) over the lease term at the commencement date. As the Company's existing leases do not have a readily determinable implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of future minimum fixed lease payments. The Company calculates its incremental borrowing rate to reflect the interest rate that it would have to pay to borrow on a collateralized basis an amount equal to the lease payments in a similar economic environment over a similar term and considers its historical borrowing activities and market data from entities with comparable credit ratings in this determination. The measurement of the right-of-use asset also includes any lease payments made prior to the commencement date (excluding any lease incentives) and initial direct costs incurred. The Company assessed its right-of-use assets for impairment as of December 31, 2023 and 2022 and determined no impairment has occurred. Lease terms may include options to extend or terminate the lease and the Company incorporates such options in the lease term when it has the unilateral right to make such an election and it is reasonably certain that the Company will exercise that option. In making this determination, the Company considers its prior renewal and termination history and planned usage of the assets under lease, incorporating expected market conditions. For operating leases, lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases includes both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. The Company expenses all variable lease costs as incurred. Certain leased facilities are being partially or fully vacated as part of the 2022 Restructuring Plan and for some of those facilities, the Company has no plans to enter into sublease agreements. Accordingly, the Company accelerated the amortization of those lease assets through the planned cease-use date of each facility, resulting in additional amortization expense of $1.0 million and $1.6 million in the years ended December 31, 2023 and 2022, respectively. No variable lease costs were accrued in the year ended December 31, 2023 for future estimated variable expenses related to assets partially or fully vacated with no intent or ability to sublease. Variable lease costs for the year ended December 31, 2022 included accruals of $1.0 million for all estimated future variable lease costs related to those facilities. The Company did not record any accelerated amortization or estimated future variable lease costs in the year ended December 31, 2023 or 2022 related to the 2020 Restructuring Plan. The Company accelerated amortization totaling $0.8 million in the year ended December 31, 2021 for certain leased facilities that were vacated in 2021 as part of the consolidation of certain sites following the ECI Acquisition. The Company did not record estimated future variable lease costs in the year ended December 31, 2021 related to the 2020 Restructuring Plan. In connection with the 2019 Restructuring Initiative, certain leased facilities were partially or fully vacated as the Company consolidated its facilities, with no plans to enter into sublease agreements for certain of those facilities. The Company did not accelerate amortization or record liabilities for future estimated variable lease costs in the years ended December 31, 2023 or 2022. In the year ended December 31, 2021, the Company accelerated amortization of $3.4 million for certain leased facilities that were vacated in those years and recorded liabilities aggregating $1.4 million for all future estimated variable lease costs related to those facilities. All incremental accelerated amortization and accrual for all estimated future variable lease costs are included in Restructuring and related expense in the Company's consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021. At December 31, 2023 and 2022 , the Company had accruals of $1.5 million and $2.0 million, respectively, for all future anticipated variable lease costs related to these facilities. The Company may incur additional future expense if it is unable to sublease other locations included in the Facilities Initiative. In addition, in the year ended December 31, 2021, this accelerated amortization and provision for future estimated variable lease costs was partially offset by the recognition of $2.1 million of income in conjunction with lease amendments that modified the Company's obligation and rentable square footage at a site in North Carolina. The Company leases its corporate offices and other facilities under operating leases, which expire at various times through 2033. The Company's right-of-use lease assets and lease liabilities at December 31, 2023 and 2022 were as follows (in thousands): December 31, Classification 2023 2022 Assets: Operating lease assets Operating lease right-of-use assets $ 39,783 $ 44,888 Liabilities: Current Operating Operating lease liabilities $ 15,739 $ 15,416 Non-Current Operating Operating lease liabilities, net of current 38,711 46,183 Total lease liabilities $ 54,450 $ 61,599 The components of lease expense for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Operating lease cost* $ 18,767 $ 21,121 $ 21,828 Finance lease cost: Amortization of leased assets — 287 695 Interest on lease liabilities — 13 67 Short-term lease cost 13,978 14,209 13,250 Variable lease costs (costs excluded from minimum fixed lease payments)** 3,364 4,007 4,030 Sublease income (1,376) (1,647) (1,496) Net lease cost $ 34,733 $ 37,990 $ 38,374 * Operating lease costs for the years ended December 31, 2023, 2022 and 2021 include $1.0 million, $1.6 million, and $3.4 million, respectively, of accelerated amortization for certain assets partially or fully vacated with no intent or ability to sublease. Operating lease cost ** Variable lease costs for the years ended December 31, 2022 and 2021 included accruals of $1.0 million and $1.4 million, respectively, for all future estimated variable expenses related to certain assets partially or fully vacated with no intent or ability to sublease. No such variable costs were accrued in the year ended December 31, 2023. Cash flow information related to the Company's leases for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 19,021 $ 20,363 22,365 Operating cash flows from finance leases $ — $ 13 67 Financing cash flows from finance leases $ — $ 595 903 Other information related to the Company's leases as of December 31, 2023 and 2022 was as follows (in thousands): December 31, 2023 2022 Weighted average remaining lease term (years): Operating leases 5.50 5.90 Weighted average discount rate: Operating leases 6.34 % 5.79 % Future minimum fixed lease payments under noncancelable leases at December 31, 2023 were as follows (in thousands): Operating leases 2024 $ 18,542 2025 10,506 2026 8,676 2027 7,569 2028 6,305 2029 and beyond 13,181 Total lease payments 64,779 Less: interest (10,329) Present value of lease liabilities $ 54,450

EMPLOYEE DEFINED CONTRIBUTION P

EMPLOYEE DEFINED CONTRIBUTION PLANS	12 Months Ended
EMPLOYEE DEFINED CONTRIBUTION PLANS	Dec. 31, 2023
Retirement Benefits [Abstract]
EMPLOYEE DEFINED CONTRIBUTION PLANS	EMPLOYEE DEFINED CONTRIBUTION PLANS The Company offers 401(k) savings plans to eligible employees. The Company matches 50% of each employee's contributions to the 401(k) program up to 4% of the employee's eligible earnings, for a maximum match of 2% of eligible earnings. The Company recorded expense related to its employee defined contribution plans aggregating $3.0 million, $3.3 million and $3.5 million in the years ended December 31, 2023, 2022 and 2021, respectively. The Company has defined benefit retirement plans that cover certain employees at various international locations. The Company's policy is to contribute amounts at least sufficient to satisfy the minimum amount required by applicable law and regulations or to directly pay benefits where appropriate. Benefits under the defined benefit plans are typically based either on years of service and the employee's compensation (generally during a fixed number of years immediately before retirement) or on annual credits. The range of assumptions that are used for these non-U.S. defined benefit plans reflect the different economic environments within the various countries. A reconciliation of the changes in the benefit obligations and fair value of the assets of the defined benefit plans for the years ended December 31, 2023 and 2022, the funded status of the plans, and the amounts recognized in the consolidated balance sheets as of December 31, 2023 and 2022 were as follows (in thousands): Year ended December 31, 2023 2022 Changes in projected benefit obligations: Projected benefit obligation, beginning of year $ 21,257 $ 26,938 Service cost 1,193 1,355 Interest cost 938 563 Participant contributions — — Plan amendments — — Net actuarial (gain) loss on obligation (402) (5,604) Settlement (1,773) (1,063) Benefits and expenses paid (444) (932) Projected benefit obligation, end of year $ 20,769 $ 21,257 Changes in plan assets: Fair value of plan assets, beginning of year $ 14,629 $ 15,303 Actual return on plan assets 183 (672) Employer contributions 975 1,954 Participant contributions 39 39 Benefits paid (2,217) (1,995) Fair value of plan assets, end of year $ 13,609 $ 14,629 Funded status at end of year $ (7,160) $ (6,628) Amounts recognized in accumulated other comprehensive income consist of: Prior service (credit) cost $ (3,161) $ (3,481) Net actuarial (gain) loss (1,100) (1,704) $ (4,261) $ (5,185) Amounts recognized in the consolidated balance sheets consist of: Other assets (non-current pension asset) $ 1,013 $ 552 Accrued expenses and other (current pension liability) (764) (803) Other long-term liabilities (non-current pension liability) (7,409) (6,377) Net amount recognized $ (7,160) $ (6,628) The increase in the underfunded status of the Company's defined benefit plans at December 31, 2023 compared to December 31, 2022 was primarily the result of significant lump sum payments in Israel of $1.8 million. Plans with underfunded or non-funded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 10,811 $ 9,450 Aggregate accumulated benefit obligation $ 8,547 $ 7,418 Aggregate fair value of plan assets $ 2,638 $ 2,270 Plans with overfunded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 9,958 $ 11,807 Aggregate accumulated benefit obligation $ 7,958 $ 9,547 Aggregate fair value of plan assets $ 10,971 $ 12,359 Net periodic benefit costs for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Service cost $ 1,193 $ 1,355 $ 1,321 Interest cost 938 563 523 Expected return on plan assets (607) (266) (314) Plan asset expenses — — — Settlement charge (credit) (417) 808 — Amortization of prior service cost (320) (320) — Amortization of net (gain) loss (165) 275 81 Net periodic benefit costs $ 622 $ 2,415 $ 1,611 Expected benefit payments for the next ten years are as follows (in thousands): Years ending December 31, 2024 $ 1,436 2025 1,086 2026 1,423 2027 2,120 2028 2,435 2029 to 2033 10,733 $ 19,233 The changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before tax for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Net loss (gain) $ 22 $ (4,666) $ 4,201 Prior service (credit) cost — — (3,801) Amortization of net gain (loss) 165 (275) (81) Amortization of prior service credit (cost) 320 320 — Settlement credit (charge) 417 (808) — Total recognized in other comprehensive income (loss) $ 924 $ (5,429) $ 319 The Company defers all actuarial gains and losses resulting from variances between actual results and economic estimates or actuarial assumptions. The unrecognized actuarial gains and losses are recorded as unrealized pension actuarial gains (losses) in the Company's consolidated balance sheets as a component of Accumulated other comprehensive income. These unrecognized gains and losses are amortized as a component of net periodic benefit cost when the net gains and losses exceed 10% of the greater of the market value of plan assets or the projected benefit obligation at the beginning of the year. The principal weighted average assumptions used to determine the benefit obligation at December 31, 2023 and 2022 were as follows: December 31, 2023 2022 Discount rate 4.65 % 4.74 % Rate of compensation increase 3.95 % 4.02 % The principal weighted average assumptions used to determine net period benefit cost for the years ended December 31, 2023, 2022 and 2021 were as follows: Year ended December 31, 2023 2022 2021 Discount rate 4.74 % 2.24 % 2.16 % Expected long-term return on plan assets 4.34 % 1.79 % 2.06 % Rate of compensation increase 4.02 % 3.90 % 2.41 % Assumed discount rates are used in the measurement of the projected and accumulated benefit obligations, as well as the service and interest cost components of net periodic pension cost. Estimated discount rates reflect the rates at which the pension benefits could be effectively settled. For each defined benefit plan, the Company chooses an estimated discount rate from a readily available market index rate, based upon high-quality fixed income investments, specific to the country or economic zone in which the benefits are paid and taking into account the duration of the plan and the number of participants. The Company's plans in both the Netherlands and Switzerland are funded through insurance contracts, which have historically provided guaranteed interest credit. The fair value of these contracts is derived from the insurance companies' assessment of the minimum value of the benefits provided by the insurance contracts. The methodology used to value these plan assets has historically assumed that the value of the plan assets equals the guaranteed insured benefits. For consistency, the same discount rate used in the valuation of the benefit obligations is used to place a value on the plan assets. The assets are assumed to grow each year in line with the discount rate, and therefore, the expected return on the assets is set equal to the discount rate. The fair value of the plan assets in Switzerland was $2.6 million at December 31, 2023 and $2.3 million at December 31, 2022. Due to the plan amendment in 2020 that changed the benefit structure of the Netherlands plan, the Company no longer has any obligation related to this plan beyond the payment of insurance premiums. Therefore, there is no projected benefit obligation and no plan assets in the Netherlands. The Company classifies the fair value of its plan assets as Level 2 in the fair value hierarchy as discussed in Note 6. During the years ended December 31, 2023 and 2022, employees in Switzerland made contributions aggregating $39,000 each year. Employee contributions to this plan are based on a fixed 5% of the relevant pensionable earnings. The Company funds this plan by contributing at least the minimum amount required by applicable regulations and as recommended by an independent actuary. During the years ended December 31, 2023, 2022 and 2021, the Company contributed $1.0 million, $2.0 million and $1.0 million, respectively, to all of its pension plans. The Company expects to contribute $1.5 million to all of its defined benefit plans in 2024.

NON-U.S. EMPLOYEE DEFINED BENEF

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS	12 Months Ended
NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS	Dec. 31, 2023
Retirement Benefits [Abstract]
NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS	EMPLOYEE DEFINED CONTRIBUTION PLANS The Company offers 401(k) savings plans to eligible employees. The Company matches 50% of each employee's contributions to the 401(k) program up to 4% of the employee's eligible earnings, for a maximum match of 2% of eligible earnings. The Company recorded expense related to its employee defined contribution plans aggregating $3.0 million, $3.3 million and $3.5 million in the years ended December 31, 2023, 2022 and 2021, respectively. The Company has defined benefit retirement plans that cover certain employees at various international locations. The Company's policy is to contribute amounts at least sufficient to satisfy the minimum amount required by applicable law and regulations or to directly pay benefits where appropriate. Benefits under the defined benefit plans are typically based either on years of service and the employee's compensation (generally during a fixed number of years immediately before retirement) or on annual credits. The range of assumptions that are used for these non-U.S. defined benefit plans reflect the different economic environments within the various countries. A reconciliation of the changes in the benefit obligations and fair value of the assets of the defined benefit plans for the years ended December 31, 2023 and 2022, the funded status of the plans, and the amounts recognized in the consolidated balance sheets as of December 31, 2023 and 2022 were as follows (in thousands): Year ended December 31, 2023 2022 Changes in projected benefit obligations: Projected benefit obligation, beginning of year $ 21,257 $ 26,938 Service cost 1,193 1,355 Interest cost 938 563 Participant contributions — — Plan amendments — — Net actuarial (gain) loss on obligation (402) (5,604) Settlement (1,773) (1,063) Benefits and expenses paid (444) (932) Projected benefit obligation, end of year $ 20,769 $ 21,257 Changes in plan assets: Fair value of plan assets, beginning of year $ 14,629 $ 15,303 Actual return on plan assets 183 (672) Employer contributions 975 1,954 Participant contributions 39 39 Benefits paid (2,217) (1,995) Fair value of plan assets, end of year $ 13,609 $ 14,629 Funded status at end of year $ (7,160) $ (6,628) Amounts recognized in accumulated other comprehensive income consist of: Prior service (credit) cost $ (3,161) $ (3,481) Net actuarial (gain) loss (1,100) (1,704) $ (4,261) $ (5,185) Amounts recognized in the consolidated balance sheets consist of: Other assets (non-current pension asset) $ 1,013 $ 552 Accrued expenses and other (current pension liability) (764) (803) Other long-term liabilities (non-current pension liability) (7,409) (6,377) Net amount recognized $ (7,160) $ (6,628) The increase in the underfunded status of the Company's defined benefit plans at December 31, 2023 compared to December 31, 2022 was primarily the result of significant lump sum payments in Israel of $1.8 million. Plans with underfunded or non-funded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 10,811 $ 9,450 Aggregate accumulated benefit obligation $ 8,547 $ 7,418 Aggregate fair value of plan assets $ 2,638 $ 2,270 Plans with overfunded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 9,958 $ 11,807 Aggregate accumulated benefit obligation $ 7,958 $ 9,547 Aggregate fair value of plan assets $ 10,971 $ 12,359 Net periodic benefit costs for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Service cost $ 1,193 $ 1,355 $ 1,321 Interest cost 938 563 523 Expected return on plan assets (607) (266) (314) Plan asset expenses — — — Settlement charge (credit) (417) 808 — Amortization of prior service cost (320) (320) — Amortization of net (gain) loss (165) 275 81 Net periodic benefit costs $ 622 $ 2,415 $ 1,611 Expected benefit payments for the next ten years are as follows (in thousands): Years ending December 31, 2024 $ 1,436 2025 1,086 2026 1,423 2027 2,120 2028 2,435 2029 to 2033 10,733 $ 19,233 The changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before tax for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Net loss (gain) $ 22 $ (4,666) $ 4,201 Prior service (credit) cost — — (3,801) Amortization of net gain (loss) 165 (275) (81) Amortization of prior service credit (cost) 320 320 — Settlement credit (charge) 417 (808) — Total recognized in other comprehensive income (loss) $ 924 $ (5,429) $ 319 The Company defers all actuarial gains and losses resulting from variances between actual results and economic estimates or actuarial assumptions. The unrecognized actuarial gains and losses are recorded as unrealized pension actuarial gains (losses) in the Company's consolidated balance sheets as a component of Accumulated other comprehensive income. These unrecognized gains and losses are amortized as a component of net periodic benefit cost when the net gains and losses exceed 10% of the greater of the market value of plan assets or the projected benefit obligation at the beginning of the year. The principal weighted average assumptions used to determine the benefit obligation at December 31, 2023 and 2022 were as follows: December 31, 2023 2022 Discount rate 4.65 % 4.74 % Rate of compensation increase 3.95 % 4.02 % The principal weighted average assumptions used to determine net period benefit cost for the years ended December 31, 2023, 2022 and 2021 were as follows: Year ended December 31, 2023 2022 2021 Discount rate 4.74 % 2.24 % 2.16 % Expected long-term return on plan assets 4.34 % 1.79 % 2.06 % Rate of compensation increase 4.02 % 3.90 % 2.41 % Assumed discount rates are used in the measurement of the projected and accumulated benefit obligations, as well as the service and interest cost components of net periodic pension cost. Estimated discount rates reflect the rates at which the pension benefits could be effectively settled. For each defined benefit plan, the Company chooses an estimated discount rate from a readily available market index rate, based upon high-quality fixed income investments, specific to the country or economic zone in which the benefits are paid and taking into account the duration of the plan and the number of participants. The Company's plans in both the Netherlands and Switzerland are funded through insurance contracts, which have historically provided guaranteed interest credit. The fair value of these contracts is derived from the insurance companies' assessment of the minimum value of the benefits provided by the insurance contracts. The methodology used to value these plan assets has historically assumed that the value of the plan assets equals the guaranteed insured benefits. For consistency, the same discount rate used in the valuation of the benefit obligations is used to place a value on the plan assets. The assets are assumed to grow each year in line with the discount rate, and therefore, the expected return on the assets is set equal to the discount rate. The fair value of the plan assets in Switzerland was $2.6 million at December 31, 2023 and $2.3 million at December 31, 2022. Due to the plan amendment in 2020 that changed the benefit structure of the Netherlands plan, the Company no longer has any obligation related to this plan beyond the payment of insurance premiums. Therefore, there is no projected benefit obligation and no plan assets in the Netherlands. The Company classifies the fair value of its plan assets as Level 2 in the fair value hierarchy as discussed in Note 6. During the years ended December 31, 2023 and 2022, employees in Switzerland made contributions aggregating $39,000 each year. Employee contributions to this plan are based on a fixed 5% of the relevant pensionable earnings. The Company funds this plan by contributing at least the minimum amount required by applicable regulations and as recommended by an independent actuary. During the years ended December 31, 2023, 2022 and 2021, the Company contributed $1.0 million, $2.0 million and $1.0 million, respectively, to all of its pension plans. The Company expects to contribute $1.5 million to all of its defined benefit plans in 2024.

INCOME TAXES

INCOME TAXES	12 Months Ended
INCOME TAXES	Dec. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The components of loss from continuing operations before income taxes consisted of the following (in thousands): Year ended December 31, 2023 2022 2021 Loss before income taxes: United States $ (5,363) $ (84,784) $ (29,985) Foreign (50,010) (27,815) (178,158) $ (55,373) $ (112,599) $ (208,143) The provision (benefit) for income taxes from continuing operations consisted of the following (in thousands): Year ended December 31, 2023 2022 2021 Provision (benefit) for income taxes: Current: Federal $ 9,927 $ (3,582) $ 5,033 State 2,790 2,573 1,836 Foreign 7,312 4,744 7,661 Total current 20,029 3,735 14,530 Deferred: Federal (10,417) (10,333) (38,027) State (1,059) (4,045) 97 Foreign 2,280 (3,873) (7,558) Total deferred (9,196) (18,251) (45,488) Total $ 10,833 $ (14,516) $ (30,958) A reconciliation of the Company's effective tax rate for continuing operations to the U.S. statutory federal rate is as follows: Year ended December 31, 2023 2022 2021 U.S. statutory income tax rate 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit (2.1) 1.8 (0.7) Foreign income taxes (9.9) (1.4) 0.5 Stock-based compensation (5.4) (2.4) (0.1) Tax credits 7.7 2.2 1.6 Uncertain tax positions 2.0 1.3 0.5 Valuation allowance (27.0) (3.8) 2.5 Non-deductible goodwill impairment — — (11.7) Other permanent adjustments (1.3) (2.6) 0.9 Permanent foreign exchange adjustments (2.3) (1.4) 0.5 Other, net (2.3) (1.8) (0.1) Effective income tax rate (19.6) % 12.9 % 14.9 % The following is a summary of the significant components of deferred income tax assets and liabilities (in thousands): December 31, 2023 2022 Assets: Net operating loss carryforwards $ 398,050 $ 413,773 Capital loss carryforwards 100,061 99,505 Tax credit carryforwards 29,541 28,902 Capitalized research and development expenses 58,959 40,668 Deferred revenue 2,042 3,510 Accrued expenses 10,901 9,068 Inventory 4,108 2,820 Stock-based compensation 1,506 1,709 Fixed assets 159 2,506 Lease liabilities 12,009 12,829 Other temporary differences 440 1,324 617,776 616,614 Valuation allowance (488,799) (488,550) Total deferred tax assets 128,977 128,064 Liabilities: Intangible assets (45,448) (55,037) Operating lease right-of-use assets (8,817) (8,519) Interest rate swap — (6,168) Unremitted foreign income (10,567) (8,441) Total deferred tax liabilities (64,832) (78,165) Total net deferred tax assets $ 64,145 $ 49,899 The deferred tax assets and liabilities based on tax jurisdictions are presented in the Company's consolidated balance sheets as follows: December 31, 2023 2022 Deferred income taxes - net noncurrent assets $ 69,761 $ 53,649 Deferred income taxes - net noncurrent liabilities (5,616) (3,750) $ 64,145 $ 49,899 At December 31, 2023, the Company had U.S. federal net operating losses ("NOLs") of $124.9 million . The Company also had U.S. state NOLs of $38.4 million . In addition, the Company had $1.6 billion of Israel NOLs. The U.S. federal NOL carryforwards expire between 2024 and 2037 . The U.S. state NOLs begin to expire in 2024 , and the Company also has indefinite-lived state NOLs. The Israel NOLs do not expire. The Company also has available federal, state and foreign income tax credit carryforwards of $29.5 million . The federal foreign tax credit carryforwards expire between 2030 and 2032 . The state tax credits, which are primarily research and development credits, begin to expire in 2024 , while others can be carried forward until exhausted. The foreign income tax credits expire in various periods. The Company has provided for income taxes on the undistributed earnings of its non-U.S. subsidiaries as of December 31, 2023, excluding Ireland and Israel. These subsidiaries, excluding Ireland and Israel, are cost-plus or limited risk distributors that are not anticipated to need to use excess funds locally. Accordingly, the Company is required to recognize and record deferred taxes in 2023. The deferred taxes, which are primarily future withholding taxes, are recorded on the entire outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings. Undistributed profits of Ireland and Israel, as well as other outside basis differences in foreign subsidiaries, were indefinitely reinvested in foreign operations. Quantification of the deferred tax liability, if any, associated with indefinitely reinvested earnings and outside basis differences was not practicable. Under the provisions of the Internal Revenue Code, the net operating losses and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service. Net operating losses and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership of significant shareholders over a three-year period in excess of 50% , as defined under sections 382 and 383 of the Internal Revenue Code, as well as similar state provisions. As a result of the Sonus and GENBAND merger in 2017, the Company has $102.6 million of U.S. federal net operating loss carryforwards remaining as of December 31, 2023 with an annual section 382 limitation of $9.7 million . The Company believes these NOLs are fully realizable. As a result of the ECI Acquisition in 2020, the Company has $23.5 million of U.S. federal NOLs remaining as of December 31, 2023 with an annual section 382 limitation of $1.1 million . The Company does not believe all of these NOLs are realizable and, therefore, have recorded a partial valuation allowance against these NOLs. The Company performed an analysis to determine if, based on all available evidence, it considered it more likely than not that some portion or all of the recorded deferred tax assets will not be realized in a future period. Accordingly, the Company has recorded a valuation allowance against its U.S. deferred tax assets of $23.4 million at December 31, 2023 and $25.5 million at December 31, 2022. The Company also maintains a valuation allowance against certain of its foreign deferred tax assets, predominantly Israel, amounting to approximately $465 million at December 31, 2023 and $463 million at December 31, 2022. The deferred tax assets recognized with no valuation allowance at December 31, 2023 and 2022 primarily relate to other foreign subsidiaries where recoverability is concluded to be more likely than not based on the Company's cost-plus compensation policy, as well as NOLs and tax credits in the U.S. that are expected to be utilized prior to expiration. A reconciliation of the Company's unrecognized tax benefits is as follows (in thousands): Year ended December 31, 2023 2022 2021 Unrecognized tax benefits at January 1 $ 12,001 $ 17,813 $ 14,054 Increases related to current year tax positions — 156 4,017 Increases related to prior period tax positions 52 40 3,168 Decreases related to the lapse of the applicable statute of limitations (821) (560) (3,087) Decreases related to prior period tax positions $ (300) $ (5,448) $ (339) Unrecognized tax benefits at December 31 $ 10,932 $ 12,001 $ 17,813 The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes. The Company had $14.0 million , $14.9 million and $21.0 million of unrecognized tax benefits, including penalties and interest, at December 31, 2023, 2022 and 2021, respectively. Of these amounts, $10.5 million , $11.2 million and $12.7 million represent the amount of unrecognized tax benefits that, if recognized, would impact the effective income tax rate for the years ended December 31, 2023, 2022 and 2021, respectively. The Company recorded income tax expense (benefit) for potential penalties and interest of $0.2 million , $(0.3) million and $1.9 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had $3.2 million and $2.9 million accrued in Other long-term liabilities for penalties and interest at December 31, 2023 and 2022, respectively. The Company believes that it is reasonably possible that $0.3 million in tax positions related to its unrecognized tax benefits will be recognized within the next twelve months. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as various state and foreign jurisdictions. Generally, the tax years 2019 through 2022 remain open to examination by the major taxing jurisdictions in which the Company operates. The Company's federal and state NOLs generated prior to 2019 could be adjusted on examination even though the year in which the loss was generated is otherwise closed by the statute of limitations. As of December 31, 2023, the Company had ongoing income tax audits in certain foreign countries. Management believes that an adequate provision has been recorded for any adjustments that may result from tax examinations.

RELATED PARTIES

RELATED PARTIES	12 Months Ended
RELATED PARTIES	Dec. 31, 2023
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES The Company recognized revenue from its largest stockholder of $12.8 million , $6.6 million and $4.5 million in the years ended December 31, 2023, 2022 and 2021, respectively. Additionally, as discussed in Note 16, certain related party stockholders participated in the Private Placement.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
COMMITMENTS AND CONTINGENCIES	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Contingencies Liabilities for Royalty Payments to the IIA Prior to the ECI Acquisition, ECI had received research and development grants from the IIA. The Company assumed ECI's contract with the IIA, which requires the Company to pay royalties to the IIA on proceeds from the sale of products which the Israeli government has supported by way of research and development grants. The royalties for grants prior to 2017 were calculated at the rates of 1.3% to 5.0% of the aggregated proceeds from the sale of such products developed at certain of the Company's R&D centers, up to an amount not exceeding 100% of such grants plus interest at LIBOR. Effective for grants approved in 2017 and thereafter, interest was calculated at the higher of LIBOR plus 1.5% to 2.75%. At December 31, 2023, the Company's maximum possible future royalties commitment, including $1.3 million of unpaid royalties accrued, was $20.4 million, including interest of $0.9 million, based on estimates of future product sales, grants received from the IIA and not yet repaid, and management's estimation of products still to be sold. Litigation The Company is often a party to disputes and legal proceedings that it considers routine and incidental to its business, including those described below. The Company believes that it has meritorious defenses to the allegations made in the pending cases and intends to vigorously defend these lawsuits; however, the Company is unable currently to forecast the ultimate outcome of these or similar matters. Since it is difficult to predict the outcome of legal proceedings, it is possible that the ultimate outcomes could materially and adversely affect the Company’s business, financial position, results of operations or cash flows. Accordingly, with respect to these proceedings, the Company is currently unable to reasonably estimate the possible loss or range of possible loss. Miller Complaint. On November 8, 2018, Ron Miller, a purported stockholder of the Company, filed a Class Action Complaint (the "Miller Complaint") in the United States District Court for the District of Massachusetts (the "Massachusetts District Court") against the Company and three of its former officers (collectively, the "Defendants"), claiming to represent a class of purchasers of Sonus common stock during the period from January 8, 2015 through March 24, 2015 and alleging violations of the federal securities laws. Similar to a previous complaint entitled Sousa et al. vs. Sonus Networks, Inc. et al., which was dismissed with prejudice by an order dated June 6, 2017, the Miller Complaint claims that the Defendants made misleading forward-looking statements concerning Sonus' expected fiscal first quarter of 2015 financial performance, which statements were also the subject of an August 7, 2018 Securities and Exchange Commission Cease and Desist Order, whose findings the Company neither admitted nor denied. The Miller plaintiffs are seeking monetary damages. After the Miller Complaint was filed, several parties filed and briefed motions seeking to be selected by the Massachusetts District Court to serve as a Lead Plaintiff in the action. On June 21, 2019, the Massachusetts District Court appointed a group as Lead Plaintiffs and the Lead Plaintiffs filed an amended complaint on July 19, 2019. On August 30, 2019, the Defendants filed a motion to dismiss the Miller Complaint and, on October 4, 2019, the Lead Plaintiffs filed an opposition to the motion to dismiss. There was an oral argument on the motion to dismiss on February 12, 2020, and on October 20, 2022 the court denied the motion to dismiss. In June 2023, the Defendants agreed to a settlement in principle with the named plaintiffs, and the settlement was preliminarily approved by the court on October 18, 2023. The proposed settlement remains subject to final approval by the affected stockholders and the court. The court has set April 24, 2024 as the hearing date for final approval of the proposed settlement. If approved, the proposed settlement would provide a release of all claims asserted in the litigation to all Defendants, who continue to deny liability. The proposed $4.5 million settlement amount was deposited into escrow in the fourth quarter of 2023 by the provider of the Company's Directors and Officers liability insurance policy. Charter Complaint. On September 19, 2022, Charter Communications Operating, LLC (“Charter”) filed two complaints against two of our subsidiaries (Sonus Networks, Inc. and Ribbon Communications Operating Company, Inc.) alleging breach of contract with respect to indemnification obligations purportedly owed to Charter in connection with Charter’s legal dispute with Sprint Communications Company L.P., which was settled by Charter in March 2022. One complaint was filed in the Supreme Court of the State of New York, in New York County; the second complaint was filed by Charter as well as co-plaintiffs Charter Communications Holding Company, LLC and Bright House Networks, LLC, in the Superior Court of the State of Delaware in and for New Castle County. In both complaints, Charter is seeking monetary damages. The Company filed its answer to the first complaint file in New York on December 7, 2022 and to the second complaint filed in Delaware on January 9, 2023. Discovery is on-going and the court in the Delaware complaint has set a preliminary trial date of January 2025. WideOpenWest Complaint. On August 9, 2023, WideOpenWest, Inc. and WideOpenWest Finance, LLC (collectively, “WOW”) filed a complaint against Ribbon alleging breach of contract with respect to indemnification obligations purportedly owed to WOW in connection with WOW’s legal dispute with Sprint Communications Company L.P., which was settled by WOW in the second quarter of 2023. The complaint was filed in the 429th Judicial District of the District Court of the State of Texas, in Collin County, Texas and has since been transferred to the 493rd Judicial District Court in Collin County. In the complaint, WOW is seeking monetary damages. The Company filed its answer to the complaint on October 5, 2023. Discovery is on-going and the court has set a preliminary trial date of December 2024.

QUARTERLY RESULTS (UNAUDITED)

QUARTERLY RESULTS (UNAUDITED)	12 Months Ended
QUARTERLY RESULTS (UNAUDITED)	Dec. 31, 2023
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS (UNAUDITED)	QUARTERLY RESULTS (UNAUDITED) The following tables present the Company's quarterly operating results for the years ended December 31, 2023 and 2022. The information for each of these quarters is unaudited and has been prepared on the same basis as the audited consolidated financial statements. In the opinion of management, all necessary adjustments, consisting only of normal recurring adjustments, have been included to present fairly the unaudited consolidated quarterly results when read in conjunction with the Company's audited consolidated financial statements and related notes. First Second Third Fourth (In thousands, except per share data) Year ended December 31, 2023 Revenue $ 186,159 $ 210,618 $ 203,161 $ 226,401 Cost of revenue 104,757 109,148 99,658 104,693 Gross profit $ 81,402 $ 101,470 $ 103,503 $ 121,708 (Loss) income from operations $ (35,189) $ (6,622) $ 856 $ 16,670 Net (loss) income $ (38,305) $ (21,479) $ (13,501) $ 7,079 (Loss) earnings per share (1): Basic $ (0.23) $ (0.13) $ (0.08) $ 0.04 Diluted $ (0.23) $ (0.13) $ (0.08) $ 0.04 Shares used in computing (loss) earnings per share: Basic 168,541 170,103 171,190 171,755 Diluted 168,541 170,103 171,190 172,990 First Second Third Fourth (In thousands, except per share data) Year ended December 31, 2022 Revenue $ 173,198 $ 205,796 $ 207,127 $ 233,639 Cost of revenue 95,143 101,246 102,809 119,626 Gross profit $ 78,055 $ 104,550 $ 104,318 $ 114,013 (Loss) income from operations $ (39,054) $ (7,239) $ (3,296) $ 1,265 Net (loss) income $ (69,975) $ (30,180) $ (18,416) $ 20,488 (Loss) earnings per share (1): Basic $ (0.47) $ (0.20) $ (0.12) $ 0.12 Diluted $ (0.47) $ (0.20) $ (0.12) $ 0.12 Shares used in computing (loss) earnings per share: Basic 149,167 150,190 158,921 168,163 Diluted 149,167 150,190 158,921 172,213 __________________________________ (1) (Loss) earnings per share is calculated independently for each of the quarters presented; accordingly, the sum of the quarterly (loss) earnings per share amounts may not equal the total calculated for the year.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net loss	$ 7,079	$ (13,501)	$ (21,479)	$ (38,305)	$ 20,488	$ (18,416)	$ (30,180)	$ (69,975)	$ (66,206)	$ (98,083)	$ (177,185)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

BASIS OF PRESENTATION AND SUM_2

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared in United States dollars, in accordance with accounting principles generally accepted in the United States ("GAAP").
Operating Segments	Operating Segments The Company's chief operating decision maker (the "CODM") is its president and chief executive officer. The CODM assesses the Company's performance based on the performance of two separate organizations within Ribbon: the Cloud and Edge segment ("Cloud and Edge") and the IP Optical Networks segment ("IP Optical Networks").
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Ribbon and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates and Judgments	Use of Estimates and Judgments The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and judgments relied upon in preparing these consolidated financial statements include accounting for business combinations, revenue recognition for multiple element arrangements, inventory valuations, assumptions used to determine the fair value of stock-based compensation and the Preferred Stock and Warrants, intangible asset and goodwill valuations, including impairments, debentures and warrants , warranty accruals, legal contingencies and recoverability of Ribbon's net deferred tax assets and the related valuation allowances. Ribbon regularly assesses these estimates and records changes in estimates in the period in which they become known. Ribbon bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Reclassifications	Reclassifications Certain reclassifications, not affecting previously reported net income (loss), have been made to the previously issued financial statements to conform to the current year presentation.
Business Combinations	Business Combinations The Company recognizes identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at the acquisition date, its estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company records adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill to the extent that it identifies adjustments to the preliminary purchase price allocation. Upon the conclusion of the measurement period or final determination of the values of assets acquired and liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations.
Revenue Recognition	Revenue Recognition The Company derives revenue from two primary sources: products and services. Product revenue includes the Company's hardware and software that function together to deliver the products' essential functionality. Software and hardware are also sold on a standalone basis. Services include customer support (software updates, upgrades and technical support), consulting, design services, installation services and training. Generally, contracts with customers contain multiple performance obligations, consisting of products and services. For these contracts, the Company accounts for individual performance obligations separately if they are considered distinct. When an arrangement contains more than one performance obligation, the Company will allocate the transaction price to each performance obligation on a relative standalone selling price basis. The Company utilizes the observable price of goods and services, including when they are sold separately to similar customers, in order to estimate standalone selling price. The Company's software licenses typically provide a perpetual right to use the Company's software. The Company also sells term-based software licenses that expire and Software-as-a-Service ("SaaS")-based software which are referred to as subscription arrangements. The Company does not customize its software nor are installation services required, as the customer has a right to utilize internal resources or a third-party service company. The software and hardware are delivered before related services are provided and are functional without professional services or customer support. The Company has concluded that its software licenses are functional intellectual property that are distinct, as the user can benefit from the software on its own. Product revenue is typically recognized upon transfer of control or when the software is made available for download, as this is the point the user of the software can direct the use of, and obtain substantially all of the remaining benefits from, the functional intellectual property. The Company begins to recognize software revenue related to the renewal of subscription software licenses at the start of the subscription period. The Company offers warranties on its products. Certain of the Company's warranties are considered to be assurance-type in nature, ensuring the product is functioning as intended. Assurance-type warranties do not represent separate performance obligations. The Company also sells separately-priced maintenance service contracts which qualify as service-type warranties and represent separate performance obligations. The Company does not allow and has no history of accepting product returns. Services revenue includes revenue from customer support and other professional services. Customer support includes software updates on a when-and-if-available basis, telephone support, integrated web-based support and bug fixes or patches. The Company sells its customer support contracts at a percentage of list or net product price. Customer support revenue is recognized ratably over the term of the customer support agreement, which is typically one year. The Company's professional services include consulting, technical support, resident engineer services, design services and installation services. Because control transfers over time, revenue is recognized based on progress toward completion of the performance obligation. The method to measure progress toward completion requires judgment and is based on the nature of the products or services to be provided. The Company generally uses the input method to measure progress for its contracts because it believes such method best depicts the transfer of assets to the customer, which occurs as the Company incurs costs for the contracts. However, in some instances, the Company uses the output method because it best depicts the transfer of asset to the customer. Under the cost-to-cost measure of progress, the progress toward completion is measured based on the ratio of costs incurred to date to the total estimated costs at completion of the performance obligation. When the measure of progress is based upon expended labor, progress toward completion is measured as the ratio of labor time expended to date versus the total estimated labor time required to complete the performance obligation. Revenue is recorded proportionally as costs are incurred or as labor is expended. Costs to fulfill these obligations include internal labor as well as subcontractor costs. Customer training includes courses offered by the Company. The related revenue is typically recognized as the training services are performed.
Preferred Stock and Warrants	Preferred Stock and Warrants The Company accounts for the Preferred Stock and Warrants as liability-classified instruments based on an assessment of their specific terms in accordance with ASC Topic 480, Distinguishing Liabilities from Equity . The fair value option was elected for the Preferred Stock, as the Company considers fair value to best reflect the expected future economic value. These liabilities are remeasured to fair value at each reporting date using the same valuation methodology applied upon issuance. The Preferred Stock is considered to be debt for our Consolidated Net Leverage Ratio covenant calculation required under our 2020 Credit Facility. The value of the Preferred Stock is calculated using the Black-Derman-Toy (BDT) stochastic yield lattice model to capture the optimal timing of repayment, increasing dividend rate and other features, and the value of the Warrants is calculated using the Black-Scholes Pricing Model.
Financial Instruments	Financial Instruments The carrying amounts of the Company's cash equivalents, accounts receivable, accounts payable and borrowings under a revolving credit facility in the Consolidated Balance Sheets approximates fair value due to the immediate or short-term nature of these financial instruments. Ribbon's term debt balance as of December 31, 2023 and 2022 of $235.4 million and $330.4 million, respectively, had a fair value of approximately $235.1 million and $323.0 million , respectively. Our Preferred Stock and Warrants liabilities as of December 31, 2023 had a combined fair value of $58.6 million , including cumulative dividends on the Preferred Stock of $3.9 million . Financial instruments with remaining maturities or that are due within one year from the balance sheet date are classified as current. Financial instruments with maturities or that are payable more than one year from the balance sheet date are classified as noncurrent.
Fair Value Option - Investment in AVCT	Fair Value Option - Investment in AVCT The Company received debentures (the "Debentures") and warrants (the "AVCT Warrants") as sale consideration in connection with its December 1, 2020 sale of the Kandy Communications Business to American Virtual Cloud Technologies, Inc. ("AVCT") (the "Kandy Sale"). On September 8, 2021 (the "Debenture Conversion Date"), the Debentures were converted into 13,700,421 shares of AVCT common stock (the "Debenture Shares"). In connection with the conversion of the Debentures to the Debenture Shares, the Company elected to use the fair value option to account for its equity investment in AVCT as permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), which then refers to ASC 820, Fair Value Measurement ("ASC 820") to provide the fair value framework for valuing such investments. In accordance with ASC 820, the Company recorded the investment in AVCT at fair value, with changes in fair value recorded as a component of Other (expense) income, net, in the consolidated statements of operations. See Note 4 for a discussion of the valuation of the Debentures, AVCT warrants and Debenture Shares. On August 29, 2022, the Company and AVCT entered into a settlement agreement which provided for, amongst other things, the cancellation of the Company's investment in the Debenture Shares and the AVCT Warrants with an aggregate fair value of $2.6 million. See Note 4 for a description of the settlement agreement with AVCT.
Transfers of Financial Assets	Transfers of Financial Assets
Foreign Currency Translation	Foreign Currency Translation For foreign subsidiaries where the functional currency is the local currency, assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Revenue and expenses are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Accumulated other comprehensive income. For foreign subsidiaries where the functional currency is the U.S. dollar, monetary assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are remeasured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Other expense, net. Realized and unrealized foreign currency exchange gains and losses arising from transactions denominated in currencies other than the subsidiary's functional currency are reflected in earnings.
Inventory	Inventory Inventory is recorded at the lower of cost or market value using the first-in, first-out convention. The Company reduces the carrying value of inventory for those items that are potentially excess, obsolete or slow-moving based on changes in customer demand, technology developments or other economic factors. Ribbon writes down evaluation equipment (equipment at customer sites for testing and evaluation) at the time of shipment to its customers, as it is probable that the inventory value will not be realized. Deferred product costs represent deferred cost of revenue for product shipments to customers prior to satisfaction of Ribbon's revenue recognition criteria. The Company classifies inventory that is not expected to be consumed within one year from the balance sheet date as noncurrent and includes such inventory as a component of Other assets.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, net of accumulated depreciation. Expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, which range from two Software development costs associated with internal use software are incurred in three stages of development: the preliminary project stage, the application development stage and the post-implementation stage. Costs incurred during the preliminary project and post-implementation stages are expensed as incurred. Certain qualifying costs incurred during the application development stage are capitalized as property and equipment. Internal use software is amortized on a straight-line basis over its estimated useful life of three years, beginning when the software is ready for its intended use.
Intangible Assets and Goodwill	Intangible Assets and Goodwill The Company's intangible assets are comprised of in-process research and development, developed technology, customer relationships, trade names, and internal use software. Intangible assets are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable based upon the estimated undiscounted cash flows. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by a comparison of the carrying amount of an asset or asset group to future net undiscounted cash flows expected to be generated by the asset or asset group. If these comparisons indicate that an asset is not recoverable, the Company will recognize an impairment loss for the amount by which the carrying value of the asset or asset group exceeds the related estimated fair value. Estimated fair value is based on either discounted future operating cash flows or appraised values, depending on the nature of the asset. The Company amortizes its intangible assets over their respective useful lives, with the exception of in-process research and development, which has an indefinite life until the product is generally available, at which time such asset is typically reclassified to developed technology, and the Company begins to amortize this asset. See Note 10 for additional information regarding the Company's intangible assets. Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. Goodwill is not amortized, but instead is tested for impairment at least annually, or more frequently if indicators of potential impairment exist, by comparing the fair value of the Company's reporting unit to its carrying value. The Company's annual test for impairment of goodwill is completed as of October 1. For the purpose of testing goodwill for impairment, all goodwill is assigned to a reporting unit, which may either be an operating segment or a portion of an operating segment. The Company's reporting units are its two operating segments, Cloud and Edge and IP Optical Networks. The Company performs a fair value analysis for each reporting unit using both an income and market approach, which encompasses a discounted cash flow analysis and a guideline public company analysis using selected multiples. The Company assesses each valuation methodology based upon the relevance and availability of the data at the time the valuation is performed and the methodologies are weighted appropriately. Any impairment charges are reported separately in the Company's consolidated statements of operations.
Stock-Based Compensation	Stock-Based Compensation The Company's stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period, and includes an estimate of the awards that will be forfeited. The Company uses the Black-Scholes valuation model for estimating the fair value of stock options on the grant date. The fair value of stock option awards is affected by the Company's stock price as well as valuation assumptions, including the volatility of Ribbon's stock price, expected term of the option, risk-free interest rate and expected dividends. The Company may grant to certain of its executives and certain other employees performance-based stock units ("PSUs") that include a market condition. The Company uses a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values of the PSUs. The Company is required to record expense for the PSUs with market conditions through their respective final vesting dates regardless of the number of shares that are ultimately earned. Once the grant date criteria have been met for a fiscal year performance period, the Company records stock-based compensation expense based on its assessment of the probability that the respective performance condition will be achieved and the level, if any, of such achievement. The Compensation Committee determines the number of shares earned, if any, after the Company's financial results for each fiscal year performance period are finalized. Upon the determination by the Compensation Committee of the number of shares that will be received upon vesting, such number of shares becomes fixed and the unamortized expense is recorded through the remainder of the service period, at which time any Performance PSUs earned, will vest pending each executive's continued employment with the Company through that date.
Concentration of Risk	Concentration of Risk The financial instruments that potentially subject Ribbon to concentrations of credit risk are cash and accounts receivable. The Company's cash equivalents were managed by one financial institution at December 31, 2023 . Historically, the Company has not experienced significant losses due to such bank depository concentration. Certain components and software licenses from third parties used in Ribbon's products are procured from single sources of supply. The failure of a supplier, including a subcontractor, to deliver on schedule could delay or interrupt Ribbon's delivery of products and thereby materially adversely affect Ribbon's revenue and operating results.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred and included as a component of Sales and marketing expense in the Company's consolidated statements of operations. Advertising expenses were $1.2 million , $1.5 million and $1.6 million for the years ended December 31, 2023, 2022 and 2021, respectively.
Loss Contingencies and Reserves	Loss Contingencies and Reserves Ribbon is subject to ongoing business risks arising in the ordinary course of business, including legal claims, that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. Ribbon regularly evaluates current information available to determine whether such amounts should be adjusted and records changes in estimates in the period they become known. An allowance for doubtful accounts is estimated based on the Company's assessment of the collectability of specific customer accounts. Ribbon accrues for royalties for technology that it licenses from vendors based on established royalty rates and usage. Ribbon is periodically contacted by third parties who claim that Ribbon's products infringe on certain intellectual property of a third party. Ribbon evaluates these claims and accrues amounts when it is probable that the obligation has been incurred and the amounts are reasonably estimable.
Warranty	Warranty one
Research and Development Grants	Research and Development Grants The Company records grants received from the Office of the Innovation Authority of the Israeli Ministry of Economics (the "IIA") as a reduction to Research and development expense. Royalties payable to the IIA are recognized pursuant to sales of related products and are included in Cost of revenue - product (see Note 26).
Accounting for Leases	Accounting for Leases The Company accounts for its leases in accordance with Accounting Standards Codification ("ASC") 842, Leases ("ASC 842") (see Note 21). The Company has operating leases for corporate offices, and research and development facilities. Operating leases are reported separately in the Company's consolidated balance sheets at December 31, 2023 and 2022. The Company has no finance leases as of December 31, 2023 or 2022. The Company determines if an arrangement is a lease at inception. A contract is determined to contain a lease component if the arrangement provides the Company with a right to control the use of an identified asset. Lease agreements may include lease and non-lease components. In such instances for all classes of underlying assets, the Company does not separate lease and non-lease components but rather, accounts for the entire arrangement under leasing guidance. Leases with an initial term of 12 months or less are not recorded on the balance sheet and lease expense for these leases is recognized on a straight-line basis over the lease term. Lease expense for minimum fixed lease payments is recognized on a straight-line basis over the lease term. The expense for finance leases would include both interest and amortization expense components, with the interest component calculated based on the effective interest method and the amortization component calculated based on straight-line amortization of the right-of-use asset over the lease term. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax reimbursements that vary over the term of the contract. Variable lease costs are not included in minimum fixed lease payments and as a result, are excluded from the measurement of the right-of-use assets and lease liabilities. The Company expenses all variable lease costs as incurred.
Accounting for Income Taxes	Accounting for Income Taxes Deferred tax assets and liabilities are recognized for the expected future consequences of events that have been reflected in the consolidated financial statements. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and operating loss carryforwards, using tax rates expected to be in effect for the years in which the differences are expected to reverse. The Company records valuation allowances to reduce deferred income tax assets to the amount that is more likely than not to be realized. The Company has provided for income taxes on the undistributed earnings of its non-U.S. subsidiaries as of December 31, 2023, excluding Ireland and Israel, which are indefinitely reinvested. Accordingly, the Company is required to recognize and record deferred taxes for 2023 on the entire outside basis differences related to the foreign subsidiaries, the largest of these differences being undistributed earnings. The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, no amount of the benefit attributable to the position is recognized. The tax benefit to be recognized of any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.
Defined Benefit Plans	Defined Benefit Plans The Company has defined benefit plans for some of its employees at various international locations. The Company recognizes retirement benefit assets or liabilities in the consolidated balance sheets reflecting the funded status of pension and other retirement benefit plans. Retirement benefit assets and liabilities are adjusted for the difference between the benefit obligations and the plan assets at fair value (measured at year-end), with the offset recorded directly to stockholders' equity through Other comprehensive income (loss), net of tax. The amount recorded in stockholders' equity represents the after-tax unamortized actuarial gains or losses, unamortized transition obligations and unamortized prior service costs.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In December 2023, the Financial Accounting Standards Board (the "FASB") issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which increases the disclosure requirements around rate reconciliation information and certain types of income taxes companies are required to pay. ASU 2023-09 will be effective for the Company beginning in 2025, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which improves reportable segment disclosure requirements, including enhancement of the disclosures of significant segment expenses and interim disclosure requirements, to enable investors to better understand an entity's overall performance and assess potential future cash flows. ASU 2023-07 will be effective for the Company annually beginning in 2024 and on an interim basis beginning in 2025, with early adoption permitted. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. In October 2023, the FASB issued ASU 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC's disclosure Update and Simplification Initiative (“ASU 2023-06”), which amends the disclosure or presentation requirements related to various subtopics in the FASB Accounting Standards Codification. This ASU was issued in response to and to align GAAP with the SEC's August 2018 final rule that updates and simplifies disclosure requirements. The effective date for the Company for each amendment will be the date on which the SEC's removal of that related disclosure requirement becomes effective, with early adoption prohibited. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements and related disclosures. On February 1, 2023, the FASB staff noted that they believe that the Pillar 2 tax, established by the OECD and intended to apply for tax years beginning in 2024, would be an alternative minimum tax and therefore deferred tax assets would not need to be recognized related to this parallel taxing system. On February 2, 2023, the OECD issued administrative guidance providing transition and safe harbor rules around the implementation of the Pillar 2 global minimum tax. Under an additional transitional safe harbor released July 17, 2023, the undertaxed profits rule top-up tax will not be applied by any constituent entity's jurisdiction of residence with respect to income earned by a company's ultimate parent entity in its jurisdiction of residence, if the ultimate parent entity's jurisdiction has a corporate tax rate of at least 20%. This transition safe harbor will apply to fiscal years beginning on or before December 31, 2025 and ending before December 31, 2026. We are closely monitoring developments and evaluating the impacts these new rules will have on our tax rate, including eligibility to qualify for these safe harbor rules. Based upon preliminary calculations for calendar year 2024, we anticipate that we will meet the safe harbors in most jurisdictions, and any remaining top-up tax should be immaterial. In March 2022, the FASB issued ASU 2022-02, Financial Instruments – Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures (“ASU 2022-02”), which eliminates the accounting guidance on troubled debt restructurings for creditors in ASC 310, Receivables (Topic 310) , and requires entities to provide disclosures about current period gross write-offs by year of origination. Also, ASU 2022-02 updates the requirements related to accounting for credit losses under ASC 326, Financial Instruments – Credit Losses (Topic 326) , and adds enhanced disclosures for creditors with respect to loan refinancings and restructurings for borrowers experiencing financial difficulty. ASU 2022-02 was effective for the Company January 1, 2023. The adoption of ASU 2022-02 did not have a material impact on the Company's consolidated financial statements. In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805): Accounting for Contract Assets and Contract Liabilities from Contracts with Customers ("ASU 2021-08"), which amends ASC 805, Business Combinations (Topic 805) , to add contract assets and contract liabilities to the list of exceptions to the recognition and measurement principles that apply to business combinations and to require that an acquiring entity recognize and measure contract assets and contract liabilities acquired in a business combination in accordance with ASC 606, Revenue from Contracts with Customers (Topic 606) ("ASC 606"). Under current GAAP, an acquirer generally recognizes such items at fair value on the acquisition date. While primarily related to contract assets and contract liabilities that were accounted for by the acquiree in accordance with ASC 606, ASU 2021-08 also applies to contract assets and contract liabilities from other contracts to which the provisions of ASC 606 apply, such as contract liabilities from the sale of nonfinancial assets within the scope of ASU 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20) . ASU 2021-08 was effective for the Company January 1, 2023. The Company believes that the adoption of ASU 2021-08 could have a material impact on its consolidated financial statements for periods including and subsequent to significant business acquisitions.

BASIS OF PRESENTATION AND SUM_3

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Information Regarding Factoring of Accounts Receivable and Associated Fees	Factoring of accounts receivable and associated fees for the years ended December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Accounts receivable sold $ 106,705 $ 74,523 Less factoring fees (2,736) (1,085) Net cash proceeds $ 103,969 $ 73,438

BUSINESS ACQUISITIONS (Tables)

BUSINESS ACQUISITIONS (Tables)	12 Months Ended
BUSINESS ACQUISITIONS (Tables)	Dec. 31, 2023
Business Combinations [Abstract]
Schedule of Components of Acquisition Related Costs	The components of Acquisition-, disposal- and integration-related expenses incurred in the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Professional and services fees (acquisition-related) $ — $ — $ 165 Professional and services fees (disposal-related) — 414 329 Integration-related expenses 4,476 5,872 7,138 $ 4,476 $ 6,286 $ 7,632

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
EARNINGS (LOSS) PER SHARE (Tables)	Dec. 31, 2023
Earnings Per Share [Abstract]
Calculations of Shares Used to Compute Loss Per Share	The shares used to compute loss per share were as follows (in thousands): Year ended December 31, 2023 2022 2021 Weighted average shares outstanding—basic 170,408 156,668 147,575 Potential dilutive common shares — — — Weighted average shares outstanding—diluted 170,408 156,668 147,575

ACCOUNTS RECEIVABLE, NET (Table

ACCOUNTS RECEIVABLE, NET (Tables)	12 Months Ended
ACCOUNTS RECEIVABLE, NET (Tables)	Dec. 31, 2023
Receivables [Abstract]
Schedule of Accounts Receivable, Net	Accounts receivable, net, consisted of the following (in thousands): December 31, 2023 2022 Accounts receivable $ 269,933 $ 268,671 Allowance for doubtful accounts (1,512) (1,427) Accounts receivable, net $ 268,421 $ 267,244
Schedule of Allowance for Doubtful Accounts	The Company's allowance for doubtful accounts activity was as follows (in thousands): Year ended December 31, Balance at Charges Charges (credits) to other accounts Write-offs Balance at 2023 $ 1,427 $ 428 $ 143 $ (486) $ 1,512 2022 $ 1,270 $ 100 $ 159 $ (102) $ 1,427 2021 $ 776 $ 553 $ 85 $ (144) $ 1,270

INVENTORY (Tables)

INVENTORY (Tables)	12 Months Ended
INVENTORY (Tables)	Dec. 31, 2023
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following (in thousands): December 31, 2023 2022 On-hand final assemblies and finished goods inventories $ 93,077 $ 85,888 Deferred cost of goods sold 3,269 1,449 96,346 87,337 Less noncurrent portion (included in Other assets) (18,825) (11,914) Current portion $ 77,521 $ 75,423

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
PROPERTY AND EQUIPMENT (Tables)	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): December 31, Useful Life 2023 2022 Equipment 2-5 years $ 77,205 $ 76,674 Software 2-5 years 34,802 33,639 Furniture and fixtures 3-5 years 3,301 3,168 Leasehold improvements Shorter of the estimated lease term or useful life 36,383 35,448 151,691 148,929 Less accumulated depreciation and amortization (109,871) (104,097) Property and equipment, net $ 41,820 $ 44,832 The net book values of the Company's property and equipment by geographic area were as follows (in thousands): December 31, 2023 2022 United States $ 20,807 $ 23,143 Canada 3,175 3,471 Asia/Pacific 8,314 8,152 Europe 957 833 Israel 8,309 8,860 Other 258 373 $ 41,820 $ 44,832

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL (Tables)	12 Months Ended
INTANGIBLE ASSETS AND GOODWILL (Tables)	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	The Company's intangible assets at December 31, 2023 and 2022 consisted of the following (in thousands): December 31, 2023 Weighted average amortization period Cost Accumulated Net Developed technology 7.84 $ 340,380 $ 239,066 $ 101,314 Customer relationships 11.86 268,140 134,743 133,397 Trade names 3.88 5,000 4,901 99 Software licenses 3.00 5,436 2,159 3,277 9.51 $ 618,956 $ 380,869 $ 238,087 December 31, 2022 Weighted average amortization period Cost Accumulated Net Developed technology 7.84 $ 340,380 $ 212,448 $ 127,932 Customer relationships 11.86 268,140 106,385 161,755 Trade names 3.88 5,000 4,658 342 Software licenses 3.00 5,186 487 4,699 9.51 $ 618,706 $ 323,978 $ 294,728
Schedule of Estimated Future Amortization Expense For Intangible Assets	Estimated future amortization expense for the Company's intangible assets at December 31, 2023 was as follows (in thousands): Years ending December 31, 2024 $ 50,800 2025 44,089 2026 39,039 2027 33,935 2028 23,400 Thereafter 46,824 $ 238,087
Schedule of Goodwill	There was no change in the carrying value of the Company's goodwill in the years ended December 31, 2022 and 2023. The components of goodwill at December 31, 2022 and 2023 were as follows (in thousands): Cloud and Edge IP Optical Networks Total Balance at December 31, 2022 Goodwill $ 392,302 $ 191,996 $ 584,298 Accumulated impairment losses (167,406) (116,000) (283,406) 224,896 75,996 300,892 Balance at December 31, 2023 Goodwill $ 392,302 $ 191,996 $ 584,298 Accumulated impairment losses (167,406) (116,000) (283,406) $ 224,896 $ 75,996 $ 300,892

ACCRUED EXPENSES AND OTHER (Tab

ACCRUED EXPENSES AND OTHER (Tables)	12 Months Ended
ACCRUED EXPENSES AND OTHER (Tables)	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses and other consisted of the following (in thousands): December 31, 2023 2022 Employee compensation and related costs $ 33,682 $ 25,994 Professional fees 19,702 17,195 Taxes payable 8,383 8,152 Other 29,920 33,929 $ 91,687 $ 85,270

WARRANTY (Tables)

WARRANTY (Tables)	12 Months Ended
WARRANTY (Tables)	Dec. 31, 2023
Guarantees and Product Warranties [Abstract]
Schedule of Changes in Accrual Balance	The changes in the Company's warranty accrual balance in the years ended December 31, 2023 and 2022 were as follows (in thousands): Year ended December 31, Balance at Provision Settlements Balance at 2023 $ 11,857 $ 5,875 $ (5,489) $ 12,243 2022 $ 13,120 $ 4,605 $ (5,868) $ 11,857

RESTRUCTURING AND FACILITIES _2

RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES (Tables)	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Accrual Activity	The components of restructuring and related expense for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Severance and related costs $ 9,875 $ 5,230 $ 4,618 Variable and other facilities-related costs 5,326 3,992 5,710 Accelerated amortization of lease assets due to cease-use 1,008 1,611 1,325 $ 16,209 $ 10,833 $ 11,653 Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ — $ 9,875 $ (9,204) $ — $ 671 A summary of the 2022 Restructuring Plan accrual activity for the years ended December 31, 2023 and 2022 are as follows (in thousands): Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ 1,164 $ — $ (1,164) $ — $ — Variable and other facilities-related costs 890 5,326 (5,748) — 468 Accelerated amortization of lease assets due to cease-use — 1,008 — (1,008) — $ 2,054 $ 6,334 $ (6,912) $ (1,008) $ 468 Balance at Initiatives Cash Net transfer to operating lease accounts Balance at Severance $ — $ 5,287 $ (4,123) $ — $ 1,164 Variable and other facilities-related costs — 3,299 (2,409) — 890 Accelerated amortization of lease assets due to cease-use — 1,611 — (1,611) — $ — $ 10,197 $ (6,532) $ (1,611) $ 2,054

DEBT (Tables)

DEBT (Tables)	12 Months Ended
DEBT (Tables)	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long Term Debt	The Company had the following outstanding borrowings, unamortized debt issuance costs, letters of credit, interest rates, and remaining borrowing capacity under the 2020 Credit Facility as of December 31, 2023 and 2022, respectively: December 31, December 31, Current portion of Term Debt $ 35,102 $ 20,058 Long-term Debt, net of Current: Long-term Debt, net of Current (Face Amount) $ 200,293 $ 310,395 Unamortized Debt Issuance Costs - Contra-Liability (2,811) (4,125) Long-term Debt, net of Current $ 197,482 $ 306,270 Total Face Amount of Borrowings $ 235,395 $ 330,453 Unamortized Debt Issuance Costs: Other Assets $ 557 $ 798 Long-Term Debt - Contra Liability 2,811 4,125 Total Unamortized Debt Issuance Costs $ 3,368 $ 4,923 Letters of Credit Outstanding $ 2,711 $ 3,272 Remaining Borrowing Capacity $ 72,289 $ 96,728 Average Interest Rates: Term Loan 10.0 % 5.4 % Letters of Credit 4.5 % 4.5 %
Schedule of Debt Maturities	The Company's debt maturities as of December 31, 2023 were as follows: Years ending December 31, 2024 35,102 2025 200,293 235,395

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	12 Months Ended
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Impact of Derivative Financial Instrument on Condensed Consolidated Statement of Operations	The impact of the Company’s derivative financial instrument on its consolidated statement of comprehensive (loss) income for the years ended December 31, 2023 and 2022 was as follows, net of tax (in thousands): Year ended December 31, 2023 2022 Gain (loss) recognized in other comprehensive income (loss) on swap, net of tax $ (2,715) $ 22,456 Amount reclassified from accumulated other comprehensive income to other expense, net upon sale of swap, net of tax (5,099) — Amount reclassified from accumulated other comprehensive income to interest expense (7,300) (3,135) Unrealized gain (loss) on interest rate swap, net of reclassifications and amortization $ (15,114) $ 19,321
Schedule of Derivative Liability Designed as a Hedging Instrument	The fair values and locations in the consolidated balance sheet at December 31, 2022 of the Company's derivative assets (liabilities) designated as a hedging instrument were as follows (in thousands): Balance sheet location December 31, 2022 Interest rate derivative - asset derivative Other current assets $ 13,212 Interest rate derivative - asset derivative Other assets 12,216 $ 25,428

PREFERRED STOCK AND WARRANTS (T

PREFERRED STOCK AND WARRANTS (Tables)	12 Months Ended
PREFERRED STOCK AND WARRANTS (Tables)	Dec. 31, 2023
Equity [Abstract]
Schedule Of Fair Value Of Preferred Stock And Warrants	fair value of the Preferred Stock and Warrants using Level 3 input. The key assumptions input into the models utilized were as follows as of December 31, 2023: Preferred Stock (BDT) Face value per share $1,000 Interest payments per year 4 Dividend rate - year 1 (paid in-kind) 9.25% Dividend rate - year 2 (paid in-kind or in cash at the Company's choice) 9.75% Dividend rate - thereafter (paid in cash) 12.00% Yield volatility 25.0% Time to maturity (in years) 1.8 Warrants (Black-Scholes) Stock price $2.90 Strike price $3.77 Risk-free rate 3.95% Volatility 60.5% Dividend yield 0.0% Time to expiration (years) 3.2 The changes in the Company's Preferred Stock and Warrant liabilities for the year ended December 31, 2023 were as follows (in thousands): Preferred stock liability Balance at January 1, 2023 $ — Issued 47,854 Cumulative dividends 3,935 Fair value change 1,548 Balance at December 31,2023 $ 53,337 Warrant liability Balance at January 1, 2023 $ — Issued 5,496 Fair value change (201) Balance at December 31,2023 $ 5,295

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	12 Months Ended
REVENUE RECOGNITION (Tables)	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Schedule of Timing of Performance Obligation	The Company's typical performance obligations include the following: Performance Obligation When Performance Obligation is Typically Satisfied When Payment is Typically Due Software and Product Revenue Software licenses (perpetual or term) Upon transfer of control; typically, when made available for download (point in time) Generally, within 30 days of invoicing except for term licenses, which may be paid for over time Software licenses (subscription) Upon activation of hosted site (over time) Generally, within 30 days of invoicing Hardware When control of the hardware passes to the customer; typically, upon delivery (point in time) Generally, within 30 days of invoicing Software upgrades Upon transfer of control; typically, when made available for download (point in time) Generally, within 30 days of invoicing Customer Support Revenue Customer support Ratably over the course of the support contract (over time) Generally, within 30 days of invoicing Professional Services Other professional services (excluding training services) As work is performed (over time) Generally, within 30 days of invoicing (upon completion of services) Training When the class is taught (point in time) Generally, within 30 days of services being performed
Schedule of Disaggregation of Revenue	The Company's total revenue for the years ended December 31, 2023, 2022 and 2021 was disaggregated geographically as follows: Year ended December 31, 2023 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 161,945 $ 133,737 $ 48,733 $ 344,415 Europe, Middle East and Africa 151,938 75,478 34,485 261,901 Asia Pacific 115,923 39,891 11,269 167,083 Other 15,344 30,546 7,050 52,940 $ 445,150 $ 279,652 $ 101,537 $ 826,339 Year ended December 31, 2022 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 175,189 $ 132,655 $ 44,819 $ 352,663 Europe, Middle East and Africa 147,523 75,948 29,310 252,781 Asia Pacific 95,828 41,677 13,594 151,099 Other 24,140 31,815 7,262 63,217 $ 442,680 $ 282,095 $ 94,985 $ 819,760 Year ended December 31, 2021 Product revenue Service revenue (maintenance) Service revenue (professional services) Total revenue United States $ 196,058 $ 132,683 $ 47,296 $ 376,037 Europe, Middle East and Africa 138,203 79,475 30,349 248,027 Asia Pacific 92,803 41,945 18,183 152,931 Other 25,978 32,218 9,766 67,962 $ 453,042 $ 286,321 $ 105,594 $ 844,957 The Company's product revenue from its direct sales program and from indirect sales through its channel partner program for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Indirect sales through channel program $ 157,495 $ 131,998 $ 117,065 Direct sales 287,655 310,682 335,977 $ 445,150 $ 442,680 $ 453,042 The Company's product revenue from sales to enterprise customers and from sales to service provider customers for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Sales to enterprise customers $ 143,853 $ 125,664 $ 111,494 Sales to service provider customers 301,297 317,016 341,548 $ 445,150 $ 442,680 $ 453,042 The Company's product revenue and service revenue components by segment for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Product revenue Cloud and Edge 184,730 215,770 248,570 IP Optical Networks 260,420 226,910 204,472 Total product revenue 445,150 442,680 453,042 Service revenue Maintenance Cloud and Edge 219,939 222,238 228,321 IP Optical Networks 59,713 59,857 58,000 Total maintenance revenue 279,652 282,095 286,321 Professional services Cloud and Edge 72,979 70,130 79,765 IP Optical Networks 28,558 24,855 25,829 Total professional services revenue 101,537 94,985 105,594 Total service revenue 381,189 377,080 391,915
Schedule of Customer Assets and Liabilities	The changes in the Company's accounts receivable, unbilled receivables and deferred revenue balances for the years ended December 31, 2023 and 2022 were as follows (in thousands): Accounts receivable Unbilled accounts receivable Deferred revenue (current) Deferred revenue (long-term) Balance at January 1, 2023 $ 170,969 $ 96,275 $ 113,939 $ 19,254 Increase (decrease), net 15,969 (14,792) (558) (36) Balance at December 31, 2023 $ 186,938 $ 81,483 $ 113,381 $ 19,218 Accounts receivable Unbilled accounts receivable Deferred revenue (current) Deferred revenue (long-term) Balance at January 1, 2022 $ 208,972 $ 73,945 $ 109,119 $ 20,619 Increase (decrease), net (38,003) 22,330 4,820 (1,365) Balance at December 31, 2022 $ 170,969 $ 96,275 $ 113,939 $ 19,254

OPERATING SEGMENT INFORMATION (

OPERATING SEGMENT INFORMATION (Tables)	12 Months Ended
OPERATING SEGMENT INFORMATION (Tables)	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	The tables below provide revenue, adjusted gross profit and depreciation expense by reportable segment for the years ended December 31, 2023, 2022 and 2021 (in thousands): Year ended December 31, Revenue 2023 2022 2021 Segment revenue: Cloud and Edge $ 477,647 $ 508,137 $ 556,656 IP Optical Networks 348,692 311,623 288,301 Total revenue $ 826,339 $ 819,760 $ 844,957 Year ended December 31, Adjusted gross profit 2023 2022 2021 Segment adjusted gross profit: Cloud and Edge $ 314,594 $ 330,395 $ 370,504 IP Optical Networks 124,436 104,711 114,496 Total segment adjusted gross profit 439,030 435,106 485,000 Stock-based compensation expense (2,657) (2,628) (1,997) Amortization of acquired technology (28,290) (31,542) (38,343) Gross profit $ 408,083 $ 400,936 $ 444,660 Year ended December 31, Depreciation expense 2023 2022 2021 Segment depreciation expense: Cloud and Edge $ 9,798 $ 10,758 $ 12,269 IP Optical Networks 4,307 4,537 4,693 Total depreciation expense $ 14,105 $ 15,295 $ 16,962

MAJOR CUSTOMERS (Tables)

MAJOR CUSTOMERS (Tables)	12 Months Ended
MAJOR CUSTOMERS (Tables)	Dec. 31, 2023
Risks and Uncertainties [Abstract]
Schedule of Customers Contributing 10% or More of the Revenue	The following customers contributed 10% or more of the Company's revenue in at least one of the years ended December 31, 2023, 2022 and 2021: Year ended December 31, 2023 2022 2021 Verizon Communications Inc. 11% 15% 16%

STOCK-BASED COMPENSATION PLANS

STOCK-BASED COMPENSATION PLANS (Tables)	12 Months Ended
STOCK-BASED COMPENSATION PLANS (Tables)	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Activity Related to Unvested Restricted Stock Grants	The activity related to the Company's RSUs for the year ended December 31, 2023 was as follows: Shares Weighted Unvested balance at January 1, 2023 7,649,747 $ 3.96 Granted 4,991,829 $ 2.88 Vested (4,840,738) $ 3.99 Forfeited (709,470) $ 3.97 Unvested balance at December 31, 2023 7,091,368 $ 3.18
Schedule of Activity Related to Performance Stock Awards	The activity related to the Company's PSUs for the year ended December 31, 2023 was as follows: Shares Weighted Unvested balance at January 1, 2023 6,653,503 $ 2.52 Granted 1,800,202 $ 3.26 Vested (381,071) $ 6.91 Forfeited (1,774,703) $ 4.05 Unvested balance at December 31, 2023 6,297,931 $ 2.07
Schedule of Stock-Based Compensation Expenses Which are Included in Condensed Consolidated Statement of Operations	The consolidated statements of operations included stock-based compensation for the years ended December 31, 2023, 2022 and 2021 as follows (in thousands): Year ended December 31, 2023 2022 2021 Product cost of revenue $ 510 $ 471 $ 313 Service cost of revenue 2,147 2,157 1,684 Research and development 4,933 5,108 4,253 Sales and marketing 7,111 6,074 7,218 General and administrative 7,105 4,897 5,950 $ 21,806 $ 18,707 $ 19,418

LEASES (Tables)

LEASES (Tables)	12 Months Ended
LEASES (Tables)	Dec. 31, 2023
Leases [Abstract]
Schedule of Right-Of-Use Lease Assets and Lease Liabilities	The Company's right-of-use lease assets and lease liabilities at December 31, 2023 and 2022 were as follows (in thousands): December 31, Classification 2023 2022 Assets: Operating lease assets Operating lease right-of-use assets $ 39,783 $ 44,888 Liabilities: Current Operating Operating lease liabilities $ 15,739 $ 15,416 Non-Current Operating Operating lease liabilities, net of current 38,711 46,183 Total lease liabilities $ 54,450 $ 61,599
Schedule of Components Of Lease Expense	The components of lease expense for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Operating lease cost* $ 18,767 $ 21,121 $ 21,828 Finance lease cost: Amortization of leased assets — 287 695 Interest on lease liabilities — 13 67 Short-term lease cost 13,978 14,209 13,250 Variable lease costs (costs excluded from minimum fixed lease payments)** 3,364 4,007 4,030 Sublease income (1,376) (1,647) (1,496) Net lease cost $ 34,733 $ 37,990 $ 38,374 * Operating lease costs for the years ended December 31, 2023, 2022 and 2021 include $1.0 million, $1.6 million, and $3.4 million, respectively, of accelerated amortization for certain assets partially or fully vacated with no intent or ability to sublease. Operating lease cost ** Variable lease costs for the years ended December 31, 2022 and 2021 included accruals of $1.0 million and $1.4 million, respectively, for all future estimated variable expenses related to certain assets partially or fully vacated with no intent or ability to sublease. No such variable costs were accrued in the year ended December 31, 2023. Cash flow information related to the Company's leases for the years ended December 31, 2023, 2022 and 2021 was as follows (in thousands): Year ended December 31, 2023 2022 2021 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 19,021 $ 20,363 22,365 Operating cash flows from finance leases $ — $ 13 67 Financing cash flows from finance leases $ — $ 595 903 Other information related to the Company's leases as of December 31, 2023 and 2022 was as follows (in thousands): December 31, 2023 2022 Weighted average remaining lease term (years): Operating leases 5.50 5.90 Weighted average discount rate: Operating leases 6.34 % 5.79 %
Schedule of Future Minimum Fixed Operating Lease Payments	Future minimum fixed lease payments under noncancelable leases at December 31, 2023 were as follows (in thousands): Operating leases 2024 $ 18,542 2025 10,506 2026 8,676 2027 7,569 2028 6,305 2029 and beyond 13,181 Total lease payments 64,779 Less: interest (10,329) Present value of lease liabilities $ 54,450
Schedule of Future Minimum Fixed Finance Lease Payments	Future minimum fixed lease payments under noncancelable leases at December 31, 2023 were as follows (in thousands): Operating leases 2024 $ 18,542 2025 10,506 2026 8,676 2027 7,569 2028 6,305 2029 and beyond 13,181 Total lease payments 64,779 Less: interest (10,329) Present value of lease liabilities $ 54,450

NON-U.S. EMPLOYEE DEFINED BEN_2

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS (Tables)	12 Months Ended
NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS (Tables)	Dec. 31, 2023
Retirement Benefits [Abstract]
Schedule of Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	A reconciliation of the changes in the benefit obligations and fair value of the assets of the defined benefit plans for the years ended December 31, 2023 and 2022, the funded status of the plans, and the amounts recognized in the consolidated balance sheets as of December 31, 2023 and 2022 were as follows (in thousands): Year ended December 31, 2023 2022 Changes in projected benefit obligations: Projected benefit obligation, beginning of year $ 21,257 $ 26,938 Service cost 1,193 1,355 Interest cost 938 563 Participant contributions — — Plan amendments — — Net actuarial (gain) loss on obligation (402) (5,604) Settlement (1,773) (1,063) Benefits and expenses paid (444) (932) Projected benefit obligation, end of year $ 20,769 $ 21,257 Changes in plan assets: Fair value of plan assets, beginning of year $ 14,629 $ 15,303 Actual return on plan assets 183 (672) Employer contributions 975 1,954 Participant contributions 39 39 Benefits paid (2,217) (1,995) Fair value of plan assets, end of year $ 13,609 $ 14,629 Funded status at end of year $ (7,160) $ (6,628) Amounts recognized in accumulated other comprehensive income consist of: Prior service (credit) cost $ (3,161) $ (3,481) Net actuarial (gain) loss (1,100) (1,704) $ (4,261) $ (5,185) Amounts recognized in the consolidated balance sheets consist of: Other assets (non-current pension asset) $ 1,013 $ 552 Accrued expenses and other (current pension liability) (764) (803) Other long-term liabilities (non-current pension liability) (7,409) (6,377) Net amount recognized $ (7,160) $ (6,628)
Schedule of Accumulated Benefit Obligations	Plans with underfunded or non-funded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 10,811 $ 9,450 Aggregate accumulated benefit obligation $ 8,547 $ 7,418 Aggregate fair value of plan assets $ 2,638 $ 2,270 Plans with overfunded accumulated benefit obligations at December 31, 2023 and 2022 were as follows (in thousands): December 31, 2023 2022 Aggregate projected benefit obligation $ 9,958 $ 11,807 Aggregate accumulated benefit obligation $ 7,958 $ 9,547 Aggregate fair value of plan assets $ 10,971 $ 12,359
Schedule of Net Benefit Costs	Net periodic benefit costs for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Service cost $ 1,193 $ 1,355 $ 1,321 Interest cost 938 563 523 Expected return on plan assets (607) (266) (314) Plan asset expenses — — — Settlement charge (credit) (417) 808 — Amortization of prior service cost (320) (320) — Amortization of net (gain) loss (165) 275 81 Net periodic benefit costs $ 622 $ 2,415 $ 1,611
Schedule of Expected Benefit Payments	Expected benefit payments for the next ten years are as follows (in thousands): Years ending December 31, 2024 $ 1,436 2025 1,086 2026 1,423 2027 2,120 2028 2,435 2029 to 2033 10,733 $ 19,233
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss)	The changes in plan assets and benefit obligations recognized in other comprehensive income (loss) before tax for the years ended December 31, 2023, 2022 and 2021 were as follows (in thousands): Year ended December 31, 2023 2022 2021 Net loss (gain) $ 22 $ (4,666) $ 4,201 Prior service (credit) cost — — (3,801) Amortization of net gain (loss) 165 (275) (81) Amortization of prior service credit (cost) 320 320 — Settlement credit (charge) 417 (808) — Total recognized in other comprehensive income (loss) $ 924 $ (5,429) $ 319
Schedule of Assumptions Used	The principal weighted average assumptions used to determine the benefit obligation at December 31, 2023 and 2022 were as follows: December 31, 2023 2022 Discount rate 4.65 % 4.74 % Rate of compensation increase 3.95 % 4.02 % The principal weighted average assumptions used to determine net period benefit cost for the years ended December 31, 2023, 2022 and 2021 were as follows: Year ended December 31, 2023 2022 2021 Discount rate 4.74 % 2.24 % 2.16 % Expected long-term return on plan assets 4.34 % 1.79 % 2.06 % Rate of compensation increase 4.02 % 3.90 % 2.41 %

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
INCOME TAXES (Tables)	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Income (Loss) Before Taxes	The components of loss from continuing operations before income taxes consisted of the following (in thousands): Year ended December 31, 2023 2022 2021 Loss before income taxes: United States $ (5,363) $ (84,784) $ (29,985) Foreign (50,010) (27,815) (178,158) $ (55,373) $ (112,599) $ (208,143)
Schedule of Income Tax Expense (Benefit)	The provision (benefit) for income taxes from continuing operations consisted of the following (in thousands): Year ended December 31, 2023 2022 2021 Provision (benefit) for income taxes: Current: Federal $ 9,927 $ (3,582) $ 5,033 State 2,790 2,573 1,836 Foreign 7,312 4,744 7,661 Total current 20,029 3,735 14,530 Deferred: Federal (10,417) (10,333) (38,027) State (1,059) (4,045) 97 Foreign 2,280 (3,873) (7,558) Total deferred (9,196) (18,251) (45,488) Total $ 10,833 $ (14,516) $ (30,958)
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the Company's effective tax rate for continuing operations to the U.S. statutory federal rate is as follows: Year ended December 31, 2023 2022 2021 U.S. statutory income tax rate 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit (2.1) 1.8 (0.7) Foreign income taxes (9.9) (1.4) 0.5 Stock-based compensation (5.4) (2.4) (0.1) Tax credits 7.7 2.2 1.6 Uncertain tax positions 2.0 1.3 0.5 Valuation allowance (27.0) (3.8) 2.5 Non-deductible goodwill impairment — — (11.7) Other permanent adjustments (1.3) (2.6) 0.9 Permanent foreign exchange adjustments (2.3) (1.4) 0.5 Other, net (2.3) (1.8) (0.1) Effective income tax rate (19.6) % 12.9 % 14.9 %
Summary of Deferred Tax Assets and Liabilities	The following is a summary of the significant components of deferred income tax assets and liabilities (in thousands): December 31, 2023 2022 Assets: Net operating loss carryforwards $ 398,050 $ 413,773 Capital loss carryforwards 100,061 99,505 Tax credit carryforwards 29,541 28,902 Capitalized research and development expenses 58,959 40,668 Deferred revenue 2,042 3,510 Accrued expenses 10,901 9,068 Inventory 4,108 2,820 Stock-based compensation 1,506 1,709 Fixed assets 159 2,506 Lease liabilities 12,009 12,829 Other temporary differences 440 1,324 617,776 616,614 Valuation allowance (488,799) (488,550) Total deferred tax assets 128,977 128,064 Liabilities: Intangible assets (45,448) (55,037) Operating lease right-of-use assets (8,817) (8,519) Interest rate swap — (6,168) Unremitted foreign income (10,567) (8,441) Total deferred tax liabilities (64,832) (78,165) Total net deferred tax assets $ 64,145 $ 49,899 The deferred tax assets and liabilities based on tax jurisdictions are presented in the Company's consolidated balance sheets as follows: December 31, 2023 2022 Deferred income taxes - net noncurrent assets $ 69,761 $ 53,649 Deferred income taxes - net noncurrent liabilities (5,616) (3,750) $ 64,145 $ 49,899
Schedule of Unrecognized Tax Benefits	A reconciliation of the Company's unrecognized tax benefits is as follows (in thousands): Year ended December 31, 2023 2022 2021 Unrecognized tax benefits at January 1 $ 12,001 $ 17,813 $ 14,054 Increases related to current year tax positions — 156 4,017 Increases related to prior period tax positions 52 40 3,168 Decreases related to the lapse of the applicable statute of limitations (821) (560) (3,087) Decreases related to prior period tax positions $ (300) $ (5,448) $ (339) Unrecognized tax benefits at December 31 $ 10,932 $ 12,001 $ 17,813

QUARTERLY RESULTS (UNAUDITED) (

QUARTERLY RESULTS (UNAUDITED) (Tables)	12 Months Ended
QUARTERLY RESULTS (UNAUDITED) (Tables)	Dec. 31, 2023
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	In the opinion of management, all necessary adjustments, consisting only of normal recurring adjustments, have been included to present fairly the unaudited consolidated quarterly results when read in conjunction with the Company's audited consolidated financial statements and related notes. First Second Third Fourth (In thousands, except per share data) Year ended December 31, 2023 Revenue $ 186,159 $ 210,618 $ 203,161 $ 226,401 Cost of revenue 104,757 109,148 99,658 104,693 Gross profit $ 81,402 $ 101,470 $ 103,503 $ 121,708 (Loss) income from operations $ (35,189) $ (6,622) $ 856 $ 16,670 Net (loss) income $ (38,305) $ (21,479) $ (13,501) $ 7,079 (Loss) earnings per share (1): Basic $ (0.23) $ (0.13) $ (0.08) $ 0.04 Diluted $ (0.23) $ (0.13) $ (0.08) $ 0.04 Shares used in computing (loss) earnings per share: Basic 168,541 170,103 171,190 171,755 Diluted 168,541 170,103 171,190 172,990 First Second Third Fourth (In thousands, except per share data) Year ended December 31, 2022 Revenue $ 173,198 $ 205,796 $ 207,127 $ 233,639 Cost of revenue 95,143 101,246 102,809 119,626 Gross profit $ 78,055 $ 104,550 $ 104,318 $ 114,013 (Loss) income from operations $ (39,054) $ (7,239) $ (3,296) $ 1,265 Net (loss) income $ (69,975) $ (30,180) $ (18,416) $ 20,488 (Loss) earnings per share (1): Basic $ (0.47) $ (0.20) $ (0.12) $ 0.12 Diluted $ (0.47) $ (0.20) $ (0.12) $ 0.12 Shares used in computing (loss) earnings per share: Basic 149,167 150,190 158,921 168,163 Diluted 149,167 150,190 158,921 172,213 __________________________________ (1) (Loss) earnings per share is calculated independently for each of the quarters presented; accordingly, the sum of the quarterly (loss) earnings per share amounts may not equal the total calculated for the year.

NATURE OF THE BUSINESS (Details

NATURE OF THE BUSINESS (Details)	Dec. 31, 2023 country
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of countries (over)	30

BASIS OF PRESENTATION AND SUM_4

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Mar. 28, 2023 USD ($) $ / shares shares	Aug. 12, 2022 USD ($) $ / shares shares	Sep. 08, 2021 shares	Dec. 31, 2023 USD ($) segment $ / shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)	Aug. 29, 2022 USD ($)	Dec. 01, 2020 $ / shares shares
Property, Plant and Equipment [Line Items]
Common stock, par value (in dollars per share) \| $ / shares				$ 0.0001	$ 0.0001
Offering expenses paid				$ 0	$ 1,654	$ 0
Number of operating segments \| segment				2
Maximum measurement period from the acquisition date within which company records adjustments to the assets acquired and liabilities assumed (in years)				1 year
Revenue agreement term (in years)				1 year
Total Face Amount of Borrowings				$ 235,395	330,453
Fair value of debt				235,100	323,000
Issued				58,600
Cumulative dividends on preferred stock				3,900
Cash received from the sale of certain accounts receivable				106,705	74,523
Foreign current exchange losses (less than)				(44)	1,576	5,002
Advertising expense				1,200	1,500	1,600
Accrued expenses and other				5,400	5,300
Other long-term liabilities				6,800	6,600
Warranty				$ 12,243	11,857	13,120
Percent threshold (as a percent)				50%
Term Loan Facility \| 2020 Credit Facility
Property, Plant and Equipment [Line Items]
Total Face Amount of Borrowings				$ 235,400	330,400
General and Administrative Expense
Property, Plant and Equipment [Line Items]
Foreign current exchange losses (less than)				$ 100	1,600	$ 5,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				5 years
Software licenses
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				3 years
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				2 years
Standard product warranty period (in years)				1 year
Minimum \| Software licenses
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				2 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				5 years
Standard product warranty period (in years)				3 years
Maximum \| Software licenses
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)				5 years
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Property, Plant and Equipment [Line Items]
Fair value of AVCT units					$ 0		$ 2,600
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Kandy Communications Business
Property, Plant and Equipment [Line Items]
Number of shares of common stock entitled from warrants (in shares) \| shares								4,377,800
Exercise price of warrants (in dollars per share) \| $ / shares								$ 0.01
Debt conversion, converted instrument, shares issued (in shares) \| shares			13,700,421
Series A Preferred Stock
Property, Plant and Equipment [Line Items]
Offering expenses paid				$ 3,500
Private Placement
Property, Plant and Equipment [Line Items]
Common stock, par value (in dollars per share) \| $ / shares		$ 0.0001
Sale of stock, number of shares issued in transaction (in shares) \| shares		17,071,311
Sale of stock (in dollars per share) \| $ / shares		$ 3.05
Sale of stock, consideration received on transaction		$ 52,100
Offering expenses paid		1,700
Private Placement \| Majority Shareholder
Property, Plant and Equipment [Line Items]
Sale of stock, consideration received on transaction		$ 10,000
Preferred Stock
Property, Plant and Equipment [Line Items]
Issued				47,854
Preferred Stock \| Private Placement
Property, Plant and Equipment [Line Items]
Common stock issued in equity offering (in shares) \| shares	55,000
Share price (in dollars per share) \| $ / shares	$ 970
Warrant
Property, Plant and Equipment [Line Items]
Issued				$ 5,496
Warrant \| Series A Preferred Stock
Property, Plant and Equipment [Line Items]
Number of shares of common stock entitled from warrants (in shares) \| shares	4,900,000
Warrant \| Private Placement
Property, Plant and Equipment [Line Items]
Share price (in dollars per share) \| $ / shares	$ 3.77
Number of shares of common stock entitled from warrants (in shares) \| shares	4,858,090
Warrant \| Private Placement \| Common stock
Property, Plant and Equipment [Line Items]
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001
Exercise price of warrants (in dollars per share) \| $ / shares	$ 3.77
Warrant \| Private Placement \| Series A Preferred Stock
Property, Plant and Equipment [Line Items]
Proceeds from issuance of common stock	$ 53,400
Warrant \| Private Placement \| Series A Preferred Stock \| Beneficial Owner [Member]
Property, Plant and Equipment [Line Items]
Proceeds from issuance of common stock	$ 10,000

BASIS OF PRESENTATION AND SUM_5

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Factoring of Accounts Receivable and Associated Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Accounts receivable sold	$ 106,705	$ 74,523
Less factoring fees	(2,736)	(1,085)
Net cash proceeds	$ 103,969	$ 73,438

BUSINESS ACQUISITIONS - ECI Nar

BUSINESS ACQUISITIONS - ECI Narrative (Details)	12 Months Ended
BUSINESS ACQUISITIONS - ECI Narrative (Details)	Dec. 31, 2022 business
ECI \| ECI
Business Acquisition [Line Items]
Number of businesses divested	1

BUSINESS ACQUISITIONS - Schedul

BUSINESS ACQUISITIONS - Schedule of Acquisition- and Integration-related Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Combinations [Abstract]
Professional and services fees (acquisition-related)	$ 0	$ 0	$ 165
Professional and services fees (disposal-related)	0	414	329
Integration-related expenses	4,476	5,872	7,138
Acquisition- and integration-related	$ 4,476	$ 6,286	$ 7,632

SALE OF KANDY COMMUNICATIONS _2

SALE OF KANDY COMMUNICATIONS BUSINESS (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Sep. 08, 2021 shares	Feb. 19, 2021 day $ / shares	Dec. 01, 2020 USD ($) day $ / shares shares	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Aug. 29, 2022 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Decrease in fair value of investments				$ 0	$ 41,291	$ 71,252
Intangible assets, net				238,087	294,728
Licensing Agreements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets, net				3,277	4,699
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Fair value of AVCT units					0		$ 2,600
Decrease in fair value of investments					41,300
Payments for settlement agreement							$ 2,500
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Licensing Agreements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets, net				$ 2,400	$ 3,900
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Kandy Communications Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from sale			$ 45,000
Number of AVCT Units acquired (in shares) \| shares			43,778
Promissory note interest rate			10%
Debenture, stock price trigger (in dollars per share) \| $ / shares		$ 6	$ 6
Debenture, number of trading days \| day		40	40
Debenture, number of consecutive trading days \| day		60	60
Debt conversion, converted instrument, shares issued (in shares) \| shares	13,700,421
Number of shares of common stock entitled from warrants (in shares) \| shares			4,377,800
Exercise price of warrants (in dollars per share) \| $ / shares			$ 0.01
Decrease in fair value of investments						74,800
Loss partially offset principal of the debentures						$ 3,500

EARNINGS (LOSS) PER SHARE - Cal

EARNINGS (LOSS) PER SHARE - Calculations of Shares Used to Compute Loss Per Share (Details) - shares shares in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of weighted average shares outstanding from basic to diluted
Weighted average shares outstanding - basic (in shares)	171,755	171,190	170,103	168,541	168,163	158,921	150,190	149,167	170,408	156,668	147,575
Potential dilutive common shares (in shares)									0	0	0
Weighted average shares outstanding - diluted (in shares)	172,990	171,190	170,103	168,541	172,213	158,921	150,190	149,167	170,408	156,668	147,575

EARNINGS (LOSS) PER SHARE - Nar

EARNINGS (LOSS) PER SHARE - Narrative (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities not included in computation of diluted loss per share (in shares)	13.5	14.5	10.6
Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities not included in computation of diluted loss per share (in shares)	4.9
Exercise price of warrants (in dollars per share)	$ 3.77

ACCOUNTS RECEIVABLE, NET - Sche

ACCOUNTS RECEIVABLE, NET - Schedule of Accounts Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Receivables [Abstract]
Accounts receivable	$ 269,933	$ 268,671
Allowance for doubtful accounts	(1,512)	(1,427)	$ (1,270)	$ (776)
Accounts receivable, net	$ 268,421	$ 267,244

ACCOUNTS RECEIVABLE, NET - Sc_2

ACCOUNTS RECEIVABLE, NET - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of year	$ 1,427	$ 1,270	$ 776
Charges to expense	428	100	553
Charges (credits) to other accounts	143	159	85
Write-offs	(486)	(102)	(144)
Balance at end of year	$ 1,512	$ 1,427	$ 1,270

INVENTORY (Details)

INVENTORY (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
On-hand final assemblies and finished goods inventories	$ 93,077	$ 85,888
Deferred cost of goods sold	3,269	1,449
Gross inventory	96,346	87,337
Less noncurrent portion (included in Other assets)	(18,825)	(11,914)
Current portion	$ 77,521	$ 75,423

PROPERTY AND EQUIPMENT - Schedu

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 151,691	$ 148,929
Less accumulated depreciation and amortization	(109,871)	(104,097)
Property and equipment, net	$ 41,820	44,832
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	2 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	5 years
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 77,205	76,674
Equipment \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	2 years
Equipment \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	5 years
Software
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	3 years
Property and equipment, gross	$ 34,802	33,639
Software \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	2 years
Software \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 3,301	3,168
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	3 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, useful life (in years)	5 years
Property and equipment, gross	$ 36,383	$ 35,448

PROPERTY AND EQUIPMENT - Narrat

PROPERTY AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation and amortization of property and equipment	$ 14,105	$ 15,295	$ 16,962

PROPERTY AND EQUIPMENT - Proper

PROPERTY AND EQUIPMENT - Property and Equipment by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 41,820	$ 44,832
United States
Property, Plant and Equipment [Line Items]
Property and equipment, net	20,807	23,143
Canada
Property, Plant and Equipment [Line Items]
Property and equipment, net	3,175	3,471
Asia/Pacific
Property, Plant and Equipment [Line Items]
Property and equipment, net	8,314	8,152
Europe
Property, Plant and Equipment [Line Items]
Property and equipment, net	957	833
Israel
Property, Plant and Equipment [Line Items]
Property and equipment, net	8,309	8,860
Other
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 258	$ 373

INTANGIBLE ASSETS AND GOODWIL_2

INTANGIBLE ASSETS AND GOODWILL -Schedule of Intangible Assets and Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period (years)	9 years 6 months 3 days	9 years 6 months 3 days
Cost	$ 618,956	$ 618,706
Accumulated amortization	380,869	323,978
Net carrying value	238,087	$ 294,728
Estimated future amortization expense for intangible assets
2024	50,800
2025	44,089
2026	39,039
2027	33,935
2028	23,400
Thereafter	46,824
Total	$ 238,087
Developed technology
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period (years)	7 years 10 months 2 days	7 years 10 months 2 days
Cost	$ 340,380	$ 340,380
Accumulated amortization	239,066	212,448
Net carrying value	$ 101,314	$ 127,932
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period (years)	11 years 10 months 9 days	11 years 10 months 9 days
Cost	$ 268,140	$ 268,140
Accumulated amortization	134,743	106,385
Net carrying value	$ 133,397	$ 161,755
Trade names
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period (years)	3 years 10 months 17 days	3 years 10 months 17 days
Cost	$ 5,000	$ 5,000
Accumulated amortization	4,901	4,658
Net carrying value	$ 99	$ 342
Software licenses
Finite-Lived Intangible Assets [Line Items]
Weighted average amortization period (years)	3 years	3 years
Cost	$ 5,436	$ 5,186
Accumulated amortization	2,159	487
Net carrying value	$ 3,277	$ 4,699

INTANGIBLE ASSETS AND GOODWIL_3

INTANGIBLE ASSETS AND GOODWILL - Narrative (Details)	12 Months Ended
INTANGIBLE ASSETS AND GOODWILL - Narrative (Details)	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Number of operating segments \| segment	2
Impairment of goodwill	$ 0	$ 0	$ 116,000,000
Goodwill period change in carrying value	$ 0	$ 0

INTANGIBLE ASSETS AND GOODWIL_4

INTANGIBLE ASSETS AND GOODWILL - Schedule of Components of Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Line Items]
Goodwill	$ 584,298	$ 584,298
Accumulated impairment losses	(283,406)	(283,406)
Goodwill, Total	300,892	300,892
Cloud and Edge
Goodwill [Line Items]
Goodwill	392,302	392,302
Accumulated impairment losses	(167,406)	(167,406)
Goodwill, Total	224,896	224,896
IP Optical Networks
Goodwill [Line Items]
Goodwill	191,996	191,996
Accumulated impairment losses	(116,000)	(116,000)
Goodwill, Total	$ 75,996	$ 75,996

ACCRUED EXPENSES AND OTHER (Det

ACCRUED EXPENSES AND OTHER (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Employee compensation and related costs	$ 33,682	$ 25,994
Professional fees	19,702	17,195
Taxes payable	8,383	8,152
Other	29,920	33,929
Total	$ 91,687	$ 85,270

WARRANTY (Details)

WARRANTY (Details) - USD ($) $ in Thousands	12 Months Ended
WARRANTY (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of year	$ 11,857	$ 13,120
Provision	5,875	4,605
Settlements	(5,489)	(5,868)
Balance at end of year	$ 12,243	$ 11,857

RESTRUCTURING AND FACILITIES _3

RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES - Narrative (Details) $ in Thousands		12 Months Ended
	Jan. 02, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) employee	Dec. 31, 2021 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and related		$ 16,209	$ 10,833	$ 11,653
Restructuring reserve noncurrent		1,100	2,000
Restructuring reserve current		1,100	1,300
EA Elktro-Automatik Holding GmbH \| Subsequent Event
Restructuring Cost and Reserve [Line Items]
Fair value of total consideration	$ 5,300
2023 Restructuring Initiative
Restructuring Cost and Reserve [Line Items]
Restructuring and related		9,900
2023 Restructuring Initiative \| Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and related		9,875
2022 Restructuring Initiative
Restructuring Cost and Reserve [Line Items]
Restructuring and related		6,334	10,197
Restructuring and related expense			5,000
2022 Restructuring Initiative \| Variable and other facilities-related costs
Restructuring Cost and Reserve [Line Items]
Restructuring and related		5,326	3,299
2022 Restructuring Initiative \| Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and related		0	$ 5,287
Number of positions eliminated \| employee			70
2022 Restructuring Initiative \| Accelerated amortization of lease assets due to cease-use
Restructuring Cost and Reserve [Line Items]
Restructuring and related		$ 1,008	$ 1,611

RESTRUCTURING AND FACILITIES _4

RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES - Components of Restructuring Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Severance and related costs	$ 9,875	$ 5,230	$ 4,618
Variable and other facilities-related costs	5,326	3,992	5,710
Accelerated amortization of lease assets due to cease-use	1,008	1,611	1,325
Restructuring and related	$ 16,209	$ 10,833	$ 11,653

RESTRUCTURING AND FACILITIES _5

RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES - Restructuring Initiatives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restructuring Reserve [Roll Forward]
Initiatives charged to expense	$ 16,209	$ 10,833	$ 11,653
2022 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	2,054	0
Initiatives charged to expense	6,334	10,197
Cash payments	(6,912)	(6,532)
Net transfer to operating lease accounts	1,008	1,611
Balance at the end of the period	468	2,054	0
2023 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Initiatives charged to expense	9,900
Severance \| 2022 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	1,164	0
Initiatives charged to expense	0	5,287
Cash payments	(1,164)	(4,123)
Net transfer to operating lease accounts	0	0
Balance at the end of the period	0	1,164	0
Severance \| 2023 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	0
Initiatives charged to expense	9,875
Cash payments	(9,204)
Net transfer to operating lease accounts	0
Balance at the end of the period	671	0
Variable and other facilities-related costs \| 2022 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	890	0
Initiatives charged to expense	5,326	3,299
Cash payments	(5,748)	(2,409)
Net transfer to operating lease accounts	0	0
Balance at the end of the period	468	890	0
Accelerated amortization of lease assets due to cease-use \| 2022 Restructuring Initiative
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	0	0
Initiatives charged to expense	1,008	1,611
Cash payments	0	0
Net transfer to operating lease accounts	1,008	1,611
Balance at the end of the period	$ 0	$ 0	$ 0

DEBT - Credit Facilities (Detai

DEBT - Credit Facilities (Details)						12 Months Ended
DEBT - Credit Facilities (Details)	Mar. 24, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 10, 2022 USD ($)	Mar. 03, 2021 USD ($)	Aug. 18, 2020 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 03, 2020 USD ($)
Debt Instrument [Line Items]
Repayment of principal						$ 97,000,000	$ 73,625,000	$ 0
Letters of credit outstanding						$ 7,900,000	$ 8,300,000
2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender									$ 500,000,000
Repayment of principal		$ 10,000,000	$ 15,000,000
Accordion feature		$ 50,000,000
Percent of aggregate amount applied for repayment		50%
2020 Credit Facility \| Debt Instrument, Period Five
Debt Instrument [Line Items]
Consolidated net leverage ratio		1.25
2020 Credit Facility \| Debt Instrument, Period Four
Debt Instrument [Line Items]
Consolidated net leverage ratio		1.10
2020 Credit Facility \| Debt Instrument, Period Six
Debt Instrument [Line Items]
Consolidated net leverage ratio	1.10
2020 Credit Facility \| Debt Instrument, Period Seven
Debt Instrument [Line Items]
Consolidated net leverage ratio	1.25
2020 Credit Facility \| Maximum \| Debt Instrument, Period Five
Debt Instrument [Line Items]
Consolidated net leverage ratio	4	4.50
2020 Credit Facility \| Maximum \| Debt Instrument, Period One
Debt Instrument [Line Items]
Consolidated net leverage ratio	4.50	4.75
2020 Credit Facility \| Maximum \| Debt Instrument, Period Four
Debt Instrument [Line Items]
Consolidated net leverage ratio	3
2020 Credit Facility \| Maximum \| Debt Instrument, Period Two
Debt Instrument [Line Items]
Consolidated net leverage ratio	4.25	3.25
2020 Credit Facility \| Maximum \| Debt Instrument, Period Three
Debt Instrument [Line Items]
Consolidated net leverage ratio	4	3
Revolving Credit Facility \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender	$ 75,000,000								100,000,000
Repayments of debt	75,000,000
Debt issuance costs, gross	1,700,000
Term Loan Facility \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender									400,000,000
Letters of Credit
Debt Instrument [Line Items]
Debt interest rate						4.50%	4.50%
Letters of Credit \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender	$ 20,000,000								30,000,000
Debt interest rate	4.50%
Letters of credit outstanding						$ 2,700,000	$ 3,300,000
Letters of Credit \| 2020 Credit Facility \| SOFR
Debt Instrument [Line Items]
Basis spread on variable rate						4.50%
Swingline Loan \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender									$ 20,000,000
Term Loan Facility, Term B Loan \| Minimum \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Term Loan Facility, Term B Loan \| Maximum \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		3.50%
Term Loan Facility, Term B Loan \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender					$ 75,000,000
Term Loan Facility, Term B Loan \| 2020 Credit Facility \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					7.50%
Term Loan Facility, Term B Loan \| 2020 Credit Facility \| Minimum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Term Loan Facility, Term B Loan \| 2020 Credit Facility \| Maximum \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%
Term Loan Facility, Term B Loan \| 2020 Credit Facility \| Maximum \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Term Loan Facility, Term B Loan \| 2020 Credit Facility \| Maximum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		4.50%
Term Loan Facility, Term A Loan \| 2020 Credit Facility
Debt Instrument [Line Items]
Commitments from lender					$ 325,000,000
Term Loan Facility, Term A Loan \| 2020 Credit Facility \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%
Term Loan Facility, Term A Loan \| 2020 Credit Facility \| Minimum \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate					0.50%
Term Loan Facility, Term A Loan \| 2020 Credit Facility \| Minimum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.50%
Term Loan Facility, Term A Loan \| 2020 Credit Facility \| Maximum \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate					2.50%
Term Loan Facility, Term A Loan \| 2020 Credit Facility \| Maximum \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					3.50%
2020 Term Loan
Debt Instrument [Line Items]
Quarterly principal payment amount				$ 74,600,000
Write off of capitalized debt issuance costs						$ 2,500,000
Repayment of debt per quarter through March 31, 2024		$ 5,000,000
Repayment of debt for three quarters, thereafter		$ 10,000,000
Repayment of debt, final payment	$ 200,300,000

DEBT - Schedule of Long Term De

DEBT - Schedule of Long Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Mar. 24, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Current portion of Term Debt	$ 35,102		$ 20,058
Long-term Debt, net of Current (Face Amount)	200,293		310,395
Unamortized Debt Issuance Costs - Contra-Liability	(2,811)		(4,125)
Long-term Debt, net of Current	197,482		306,270
Total Face Amount of Borrowings	235,395		330,453
Other Assets	557		798
Long-Term Debt - Contra Liability	2,811		4,125
Total Unamortized Debt Issuance Costs	3,368		4,923
2020 Credit Facility
Line of Credit Facility [Line Items]
Remaining Borrowing Capacity	$ 72,289		$ 96,728
Term Loan
Line of Credit Facility [Line Items]
Average Interest Rates	10%		5.40%
Letters of Credit
Line of Credit Facility [Line Items]
Outstanding balance	$ 2,711		$ 3,272
Average Interest Rates	4.50%		4.50%
Letters of Credit \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Average Interest Rates		4.50%

DEBT - Schedule of Debt Maturit

DEBT - Schedule of Debt Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2024	$ 35,102
2025	200,293
Total Debt	$ 235,395	$ 330,453

DEBT - Letters of Credit and Pe

DEBT - Letters of Credit and Performance and Bid Bonds (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 7.9	$ 8.3
Letters of Credit \| 2020 Credit Facility
Line of Credit Facility [Line Items]
Letters of credit outstanding	2.7	3.3
Various Uncommitted Facilities
Line of Credit Facility [Line Items]
Letters of credit outstanding	$ 5.2	$ 5

DERIVATIVE INSTRUMENTS AND HE_3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Narrative (Details) - USD ($)					1 Months Ended	12 Months Ended
	Mar. 27, 2023	Mar. 24, 2023	Aug. 16, 2022	Jul. 22, 2022	Aug. 16, 2022	Dec. 31, 2023	Dec. 31, 2022	Mar. 31, 2020
Derivative [Line Items]
Debt balance						$ 235,395,000	$ 330,453,000
Interest Rate Swap
Derivative [Line Items]
Derivative instrument sold	$ 170,000,000	$ 170,000,000	$ 30,000,000	$ 30,000,000	$ 60,000,000
Proceeds from sale	9,800,000	9,400,000	1,600,000	1,500,000
Notional amount		170,000,000	$ 340,000,000	$ 370,000,000	340,000,000
Amount reclassified from accumulated other comprehensive income (loss) to interest expense	7,300,000				$ 3,100,000
Amortization of derivative instrument						900,000	500,000
Proceeds from sale of derivative, gross	9,400,000	9,000,000
Proceeds from derivative interest	400,000	$ 400,000
Interest rate derivative							25,428,000
Interest Rate Swap \| Level Two
Derivative [Line Items]
Interest rate derivative						0	25,400,000
2020 Credit Facility \| Interest Rate Swap
Derivative [Line Items]
Amount reclassified from accumulated other comprehensive income (loss) to interest expense	$ 12,000,000
Amortization of derivative instrument						4,700,000
Term Loan Facility \| 2020 Credit Facility
Derivative [Line Items]
Debt balance						$ 235,400,000	$ 330,400,000
Principal amount								$ 400,000,000
Fixed rate						0.904%

DERIVATIVE INSTRUMENTS AND HE_4

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Impact of Derivative Financial Instrument on Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Gain (loss) recognized in other comprehensive income (loss) on swap, net of tax			$ (2,715)	$ 22,456
Unrealized gain (loss) on interest rate swap, net of reclassifications and amortization			(15,114)	19,321
Other Income
Derivative [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense	$ (5,099)	$ 0
Interest Expense
Derivative [Line Items]
Amount reclassified from accumulated other comprehensive income to interest expense			$ (7,300)	$ (3,135)

DERIVATIVE INSTRUMENTS AND HE_5

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Fair Values and Locations in the Condensed Consolidated Balance Sheet (Details) - Interest Rate Swap $ in Thousands	Dec. 31, 2022 USD ($)
Derivative [Line Items]
Interest rate derivative - asset derivative	$ 13,212
Interest rate derivative - asset derivative	12,216
Interest rate derivative	$ 25,428

PREFERRED STOCK AND WARRANTS -

PREFERRED STOCK AND WARRANTS - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Mar. 28, 2023	Aug. 12, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Dividends Payable [Line Items]
Proceeds from issuance of preferred stock and warrant liabilities			$ 53,350	$ 0	$ 0
Offering expenses paid			0	$ 1,654	$ 0
Series A Preferred Stock
Dividends Payable [Line Items]
Proceeds from issuance of preferred stock	$ 53,400
Offering expenses paid			$ 3,500
Preferred stock, redemption, percentage year one	103%
Preferred stock, redemption, percentage year two	102%
Series A Preferred Stock \| Beneficial Owner
Dividends Payable [Line Items]
Proceeds from issuance of preferred stock	$ 10,000
Series A Preferred Stock \| Dividends Payable in Kind Year One
Dividends Payable [Line Items]
Preferred stock, dividend percentage	9.25%
Series A Preferred Stock \| Dividends Payable in Kind Year Two
Dividends Payable [Line Items]
Preferred stock, dividend percentage	9.75%
Series A Preferred Stock \| Dividends Payable In Cash Thereafter
Dividends Payable [Line Items]
Preferred stock, dividend percentage	12%
Private Placement
Dividends Payable [Line Items]
Offering expenses paid		$ 1,700
Preferred Stock \| Private Placement
Dividends Payable [Line Items]
Shares issued (in shares)	55,000
Share price (in dollars per share)	$ 970
Warrant \| Series A Preferred Stock
Dividends Payable [Line Items]
Number of shares of common stock entitled from warrants (in shares)	4,900,000
Warrant \| Private Placement
Dividends Payable [Line Items]
Share price (in dollars per share)	$ 3.77
Number of shares of common stock entitled from warrants (in shares)	4,858,090

PREFERRED STOCK AND WARRANTS _2

PREFERRED STOCK AND WARRANTS - Key Inputs (Details) - Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2023 $ / shares
Black Scholes Pricing Model \| Warrant
Dividends Payable [Line Items]
Time to maturity (in years)	3 years 2 months 12 days
Black Scholes Pricing Model \| Yield volatility \| Warrant
Dividends Payable [Line Items]
Measurement Input	0.605
Black Scholes Pricing Model \| Stock price \| Warrant
Dividends Payable [Line Items]
Measurement Input	2.90
Black Scholes Pricing Model \| Strike price \| Warrant
Dividends Payable [Line Items]
Measurement Input	3.77
Black Scholes Pricing Model \| Risk-free rate \| Warrant
Dividends Payable [Line Items]
Measurement Input	0.0395
Black Scholes Pricing Model \| Dividend yield \| Warrant
Dividends Payable [Line Items]
Measurement Input	0
Series A Preferred Stock \| Black-Derman-Toy
Dividends Payable [Line Items]
Face value per share	$ 1,000
Time to maturity (in years)	1 year 9 months 18 days
Series A Preferred Stock \| Black-Derman-Toy \| Interest payments per year
Dividends Payable [Line Items]
Measurement Input	4
Series A Preferred Stock \| Black-Derman-Toy \| Dividend rate - year 1 (paid in-kind)
Dividends Payable [Line Items]
Measurement Input	0.0925
Series A Preferred Stock \| Black-Derman-Toy \| Dividend rate - year 2 (paid in-kind or in cash at the Company's choice)
Dividends Payable [Line Items]
Measurement Input	0.0975
Series A Preferred Stock \| Black-Derman-Toy \| Dividend rate - thereafter (paid in cash)
Dividends Payable [Line Items]
Measurement Input	0.1200
Series A Preferred Stock \| Black-Derman-Toy \| Yield volatility
Dividends Payable [Line Items]
Measurement Input	0.250

PREFERRED STOCK AND WARRANTS _3

PREFERRED STOCK AND WARRANTS - Warrant and Preferred Stock Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Preferred stock liability
Issued	$ 58,600
Change in fair value of preferred stock liability	1,548	$ 0	$ 0
Warrant liability
Issued	58,600
Change in fair value of warrant liability	(201)	0	$ 0
Preferred Stock
Preferred stock liability
Beginning balance	0
Issued	47,854
Cumulative dividends	3,935
Change in fair value of preferred stock liability	1,548
Ending balance	53,337	0
Warrant liability
Issued	47,854
Warrant
Preferred stock liability
Issued	5,496
Warrant liability
Beginning balance	0
Issued	5,496
Change in fair value of warrant liability	(201)
Ending balance	$ 5,295	$ 0

REVENUE RECOGNITION - Schedule

REVENUE RECOGNITION - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 826,339	$ 819,760	$ 844,957
Cloud and Edge
Disaggregation of Revenue [Line Items]
Total revenue	477,647	508,137	556,656
IP Optical Networks
Disaggregation of Revenue [Line Items]
Total revenue	348,692	311,623	288,301
Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	445,150	442,680	453,042
Product revenue \| Cloud and Edge
Disaggregation of Revenue [Line Items]
Total revenue	184,730	215,770	248,570
Product revenue \| IP Optical Networks
Disaggregation of Revenue [Line Items]
Total revenue	260,420	226,910	204,472
Product revenue \| Sales to enterprise customers
Disaggregation of Revenue [Line Items]
Total revenue	143,853	125,664	111,494
Product revenue \| Sales to service provider customers
Disaggregation of Revenue [Line Items]
Total revenue	301,297	317,016	341,548
Product revenue \| Indirect sales through channel program
Disaggregation of Revenue [Line Items]
Total revenue	157,495	131,998	117,065
Product revenue \| Direct sales
Disaggregation of Revenue [Line Items]
Total revenue	287,655	310,682	335,977
Service
Disaggregation of Revenue [Line Items]
Total revenue	381,189	377,080	391,915
Service revenue (maintenance)
Disaggregation of Revenue [Line Items]
Total revenue	279,652	282,095	286,321
Service revenue (maintenance) \| Cloud and Edge
Disaggregation of Revenue [Line Items]
Total revenue	219,939	222,238	228,321
Service revenue (maintenance) \| IP Optical Networks
Disaggregation of Revenue [Line Items]
Total revenue	59,713	59,857	58,000
Service revenue (professional services)
Disaggregation of Revenue [Line Items]
Total revenue	101,537	94,985	105,594
Service revenue (professional services) \| Cloud and Edge
Disaggregation of Revenue [Line Items]
Total revenue	72,979	70,130	79,765
Service revenue (professional services) \| IP Optical Networks
Disaggregation of Revenue [Line Items]
Total revenue	28,558	24,855	25,829
United States
Disaggregation of Revenue [Line Items]
Total revenue	344,415	352,663	376,037
United States \| Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	161,945	175,189	196,058
United States \| Service revenue (maintenance)
Disaggregation of Revenue [Line Items]
Total revenue	133,737	132,655	132,683
United States \| Service revenue (professional services)
Disaggregation of Revenue [Line Items]
Total revenue	48,733	44,819	47,296
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenue	261,901	252,781	248,027
Europe, Middle East and Africa \| Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	151,938	147,523	138,203
Europe, Middle East and Africa \| Service revenue (maintenance)
Disaggregation of Revenue [Line Items]
Total revenue	75,478	75,948	79,475
Europe, Middle East and Africa \| Service revenue (professional services)
Disaggregation of Revenue [Line Items]
Total revenue	34,485	29,310	30,349
Asia Pacific
Disaggregation of Revenue [Line Items]
Total revenue	167,083	151,099	152,931
Asia Pacific \| Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	115,923	95,828	92,803
Asia Pacific \| Service revenue (maintenance)
Disaggregation of Revenue [Line Items]
Total revenue	39,891	41,677	41,945
Asia Pacific \| Service revenue (professional services)
Disaggregation of Revenue [Line Items]
Total revenue	11,269	13,594	18,183
Other
Disaggregation of Revenue [Line Items]
Total revenue	52,940	63,217	67,962
Other \| Product revenue
Disaggregation of Revenue [Line Items]
Total revenue	15,344	24,140	25,978
Other \| Service revenue (maintenance)
Disaggregation of Revenue [Line Items]
Total revenue	30,546	31,815	32,218
Other \| Service revenue (professional services)
Disaggregation of Revenue [Line Items]
Total revenue	$ 7,050	$ 7,262	$ 9,766

REVENUE RECOGNITION - Schedul_2

REVENUE RECOGNITION - Schedule of Customer Assets & Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounts receivable
Beginning balance	$ 170,969	$ 208,972
Increase (decrease), net	15,969	(38,003)
Ending balance	186,938	170,969
Unbilled accounts receivable
Beginning balance	96,275	73,945
Increase (decrease), net	(14,792)	22,330
Ending balance	81,483	96,275
Deferred revenue (current)
Beginning balance	113,939	109,119
Increase (decrease), net	(558)	4,820
Ending balance	113,381	113,939
Deferred revenue (long-term)
Beginning balance	19,254	20,619
Increase (decrease), net	(36)	(1,365)
Ending balance	$ 19,218	$ 19,254

REVENUE RECOGNITION - Narrative

REVENUE RECOGNITION - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue recognized	$ 108	$ 103
Customer contract expected life (in years)	5 years
Deferred sales commissions capitalized	$ 3	$ 3.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue to be recognized	$ 13
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue to be recognized	$ 4
Revenue, remaining performance obligation, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue to be recognized	$ 2
Revenue, remaining performance obligation, period	1 year

OPERATING SEGMENT INFORMATION_2

OPERATING SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended								12 Months Ended
OPERATING SEGMENT INFORMATION (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting [Abstract]
Number of reportable operating segments \| segment									2
Segment Reporting Information [Line Items]
Total revenue									$ 826,339	$ 819,760	$ 844,957
Total segment adjusted gross profit									439,030	435,106	485,000
Stock-based compensation expense									(2,657)	(2,628)	(1,997)
Amortization of acquired technology									(28,290)	(31,542)	(38,343)
Gross profit	$ 121,708	$ 103,503	$ 101,470	$ 81,402	$ 114,013	$ 104,318	$ 104,550	$ 78,055	408,083	400,936	444,660
Segment depreciation expense:
Total depreciation expense									14,105	15,295	16,962
Cloud and Edge
Segment Reporting Information [Line Items]
Total revenue									477,647	508,137	556,656
Total segment adjusted gross profit									314,594	330,395	370,504
Segment depreciation expense:
Total depreciation expense									9,798	10,758	12,269
IP Optical Networks
Segment Reporting Information [Line Items]
Total revenue									348,692	311,623	288,301
Total segment adjusted gross profit									124,436	104,711	114,496
Segment depreciation expense:
Total depreciation expense									$ 4,307	$ 4,537	$ 4,693

MAJOR CUSTOMERS (Details)

MAJOR CUSTOMERS (Details)	12 Months Ended
MAJOR CUSTOMERS (Details)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue \| Customer \| Verizon Communications Inc.
Concentration Risk [Line Items]
Concentration risk (as a percent)	11%	15%	16%

STOCK-BASED COMPENSATION PLAN_2

STOCK-BASED COMPENSATION PLANS - Narratives (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) performance_period shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Stock-based compensation
Total fair value of restricted stock awards, restricted stock units, and performance-based stock units on date vested	$ 15,571	$ 9,858	$ 40,751
Fair value of the assumed awards attributable to future stock-based compensation expense	$ 17,900
Expected period for unrecognized expense	1 year 4 months 24 days
Shares available for future issuance (in shares) \| shares	3,959,285,000
PSUs
Stock-based compensation
Total fair value of restricted stock awards, restricted stock units, and performance-based stock units on date vested	$ 2,600	$ 900	$ 1,700
PSUs, Performance Based
Stock-based compensation
Granted percentage		60%
Number of performance periods \| performance_period	3
PSUs, Market Based
Stock-based compensation
Performance period (in years)	3 years
Granted percentage			40%
Number of performance periods \| performance_period	1
Percent of performance metrics achieved	200%
RSAs
Stock-based compensation
Total fair value of restricted stock awards, restricted stock units, and performance-based stock units on date vested	$ 19,300	$ 18,100	$ 12,500
Stock Options
Stock-based compensation
Shares available for future issuance (in shares) \| shares	105,495,000
Restricted Stock, Restricted Stock Units And Performance Stock Units \| Maximum
Stock-based compensation
Performance period (in years)	3 years
Restricted Stock, Restricted Stock Units And Performance Stock Units \| Minimum
Stock-based compensation
Performance period (in years)	1 year

STOCK-BASED COMPENSATION PLAN_3

STOCK-BASED COMPENSATION PLANS - Restricted Stock Awards and Units and Performance-Based Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Weighted Average Grant Date Fair Value
Total grant date fair value of shares that vested during the period	$ 15,571	$ 9,858	$ 40,751
RSUs
Shares
Unvested balance at the beginning of the period (in shares)	7,649,747
Granted (in shares)	4,991,829
Vested (in shares)	(4,840,738)
Forfeited (in shares)	(709,470)
Unvested balance at the end of the period (in shares)	7,091,368	7,649,747
Weighted Average Grant Date Fair Value
Unvested balance at the beginning of the period (in dollars per share)	$ 3.96
Granted (in dollars per share)	2.88
Vested (in dollars per share)	3.99
Forfeited (in dollars per share)	3.97
Unvested balance at end of the period (in dollars per share)	$ 3.18	$ 3.96
RSAs
Weighted Average Grant Date Fair Value
Total grant date fair value of shares that vested during the period	$ 19,300	$ 18,100	12,500
PSUs
Shares
Unvested balance at the beginning of the period (in shares)	6,653,503
Granted (in shares)	1,800,202
Vested (in shares)	(381,071)
Forfeited (in shares)	(1,774,703)
Unvested balance at the end of the period (in shares)	6,297,931	6,653,503
Weighted Average Grant Date Fair Value
Unvested balance at the beginning of the period (in dollars per share)	$ 2.52
Granted (in dollars per share)	3.26
Vested (in dollars per share)	6.91
Forfeited (in dollars per share)	4.05
Unvested balance at end of the period (in dollars per share)	$ 2.07	$ 2.52
Total grant date fair value of shares that vested during the period	$ 2,600	$ 900	$ 1,700

STOCK-BASED COMPENSATION PLAN_4

STOCK-BASED COMPENSATION PLANS - Schedule of Stock-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock-based compensation
Stock-based compensation	$ 21,806	$ 18,707	$ 19,418
Product cost of revenue
Stock-based compensation
Stock-based compensation	510	471	313
Service cost of revenue
Stock-based compensation
Stock-based compensation	2,147	2,157	1,684
Research and development
Stock-based compensation
Stock-based compensation	4,933	5,108	4,253
Sales and marketing
Stock-based compensation
Stock-based compensation	7,111	6,074	7,218
General and administrative
Stock-based compensation
Stock-based compensation	$ 7,105	$ 4,897	$ 5,950

LEASES - Narrative (Details)

LEASES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
LEASES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease impairment	$ 0	$ 0
Finance lease impairment	0	0
Additional amortization expense	1,008	$ 1,611	$ 1,325
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]		Other expense, net
Facility Closing
Lessee, Lease, Description [Line Items]
Accrual for future anticipated variable lease costs	1,500	$ 2,000
2022 Restructuring Initiative
Lessee, Lease, Description [Line Items]
Accrual for future anticipated variable lease costs	468	2,054	0
Restructuring reserve, accrual adjustment	(1,008)	(1,611)
2022 Restructuring Initiative \| Facility Closing
Lessee, Lease, Description [Line Items]
Additional amortization expense	$ 1,000	1,600
Expense recorded for estimated future variable lease costs		$ 1,000
2020 Restructuring Initiative \| Facility Closing
Lessee, Lease, Description [Line Items]
Additional amortization expense			800
2019 Restructuring Initiative \| North Carolina Amended Lease
Lessee, Lease, Description [Line Items]
Restructuring reserve, accrual adjustment			2,100
2019 Restructuring Initiative \| Facility Closing
Lessee, Lease, Description [Line Items]
Additional amortization expense			3,400
Expense recorded for estimated future variable lease costs			$ 1,400

LEASES - Assets and Liabilities

LEASES - Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Operating lease assets	$ 39,783	$ 44,888
Current Operating
Current Operating	15,739	15,416
Non-Current Operating
Non-Current Operating	38,711	46,183
Total lease liabilities	$ 54,450	$ 61,599

LEASES - Components of Lease Ex

LEASES - Components of Lease Expense (Details)	12 Months Ended
LEASES - Components of Lease Expense (Details)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) leaseAsset	Dec. 31, 2021 USD ($)
Leases [Abstract]
Operating lease cost	$ 18,767,000	$ 21,121,000	$ 21,828,000
Finance lease cost:
Amortization of leased assets	0	287,000	695,000
Interest on lease liabilities	0	13,000	67,000
Short-term lease cost	13,978,000	14,209,000	13,250,000
Variable lease costs (costs excluded from minimum fixed lease payments)	3,364,000	4,007,000	4,030,000
Sublease income	(1,376,000)	(1,647,000)	(1,496,000)
Net lease cost	34,733,000	37,990,000	38,374,000
Accelerated amortization	1,000,000	1,600,000	3,400,000
Operating lease, lease income		$ 2,100,000
Number of lease modification assets \| leaseAsset		1
Variable lease cost accrued	0	$ 1,000,000	$ 1,400,000
Variable lease, payment	$ 0

LEASES - Other Information (Det

LEASES - Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 19,021	$ 20,363	$ 22,365
Operating cash flows from finance leases	0	13	67
Financing cash flows from finance leases	$ 0	$ 595	$ 903
Weighted average remaining lease term (years):
Operating leases	5 years 6 months	5 years 10 months 24 days
Weighted average discount rate:
Operating leases	6.34%	5.79%

LEASES - Future Minimum Lease P

LEASES - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Operating leases
2024	$ 18,542
2025	10,506
2026	8,676
2027	7,569
2028	6,305
2029 and beyond	13,181
Total lease payments	64,779
Less: interest	(10,329)
Present value of lease liabilities	$ 54,450

EMPLOYEE DEFINED CONTRIBUTION_2

EMPLOYEE DEFINED CONTRIBUTION PLANS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Employer matching percent of employees' contribution	50%
Employer matching contribution percentage of employees' gross pay	4%
Maximum employer match percentage per employee	2%
Defined contribution expense	$ 3	$ 3.3	$ 3.5

NON-U.S. EMPLOYEE DEFINED BEN_3

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, benefit obligation	$ 20,769	$ 21,257	$ 26,938
Net gains and losses amortization threshold	10%
Fair value of combined plan assets	$ 13,609	14,629	15,303
Participant contributions	$ 39	39
Fixed contributions per employee, percent	5%
Employer pension plan contributions	$ 975	1,954	1,000
Expected future employer contributions to pension plans in 2020	1,500
Israel
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, benefit obligation	1,800
Switzerland
Defined Benefit Plan Disclosure [Line Items]
Fair value of combined plan assets	2,600	2,300
Netherlands
Defined Benefit Plan Disclosure [Line Items]
Fair value of combined plan assets	$ 0	$ 0	$ 0

NON-U.S. EMPLOYEE DEFINED BEN_4

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Changes in Benefit Obligations and Fair Value of Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in projected benefit obligations:
Projected benefit obligation, beginning of year	$ 21,257	$ 26,938
Service cost	1,193	1,355	$ 1,321
Interest cost	938	563	523
Participant contributions	0	0
Plan amendments	0	0
Net actuarial (gain) loss on obligation	(402)	(5,604)
Settlement	(1,773)	(1,063)
Benefits and expenses paid	(444)	(932)
Projected benefit obligation, end of year	20,769	21,257	26,938
Changes in plan assets:
Fair value of plan assets, beginning of year	14,629	15,303
Actual return on plan assets	183	(672)
Employer contributions	975	1,954	1,000
Participant contributions	39	39
Benefits paid	(2,217)	(1,995)
Fair value of plan assets, end of year	13,609	14,629	$ 15,303
Funded status at end of year	(7,160)	(6,628)
Prior service (credit) cost	(3,161)	(3,481)
Net actuarial (gain) loss	(1,100)	(1,704)
Accumulated other comprehensive income	(4,261)	(5,185)
Amounts recognized in the consolidated balance sheets consist of:
Other assets (non-current pension asset)	1,013	552
Accrued expenses and other (current pension liability)	(764)	(803)
Other long-term liabilities (non-current pension liability)	(7,409)	(6,377)
Net amount recognized	$ (7,160)	$ (6,628)

NON-U.S. EMPLOYEE DEFINED BEN_5

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Aggregate fair value of plan assets	$ 13,609	$ 14,629	$ 15,303
Defined Benefit Plan, Underfunded or Non-funded Plan
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligation	10,811	9,450
Aggregate accumulated benefit obligation	8,547	7,418
Aggregate fair value of plan assets	2,638	2,270
Defined Benefit Plan, Overfunded Plan
Defined Benefit Plan Disclosure [Line Items]
Aggregate projected benefit obligation	9,958	11,807
Aggregate accumulated benefit obligation	7,958	9,547
Aggregate fair value of plan assets	$ 10,971	$ 12,359

NON-U.S. EMPLOYEE DEFINED BEN_6

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Service cost	$ 1,193	$ 1,355	$ 1,321
Interest cost	938	563	523
Expected return on plan assets	(607)	(266)	(314)
Plan asset expenses	0	0	0
Settlement charge (credit)	(417)	808	0
Amortization of prior service cost	$ (320)	$ (320)	$ 0
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent
Amortization of net (gain) loss	$ (165)	$ 275	$ 81
Net periodic benefit costs	$ 622	$ 2,415	$ 1,611
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent

NON-U.S. EMPLOYEE DEFINED BEN_7

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Expected Future Benefit Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Retirement Benefits [Abstract]
2024	$ 1,436
2025	1,086
2026	1,423
2027	2,120
2028	2,435
2029 to 2033	10,733
Expected future benefit payments	$ 19,233

NON-U.S. EMPLOYEE DEFINED BEN_8

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Change Recognized in Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Net loss (gain)	$ 22	$ (4,666)	$ 4,201
Prior service (credit) cost	0	0	(3,801)
Amortization of net gain (loss)	165	(275)	(81)
Amortization of prior service credit (cost)	320	320	0
Settlement credit (charge)	417	(808)	0
Total recognized in other comprehensive income (loss)	$ 924	$ (5,429)	$ 319

NON-U.S. EMPLOYEE DEFINED BEN_9

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Assumptions for Benefit Obligation (Details)	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Discount rate	4.65%	4.74%
Rate of compensation increase	3.95%	4.02%

NON-U.S. EMPLOYEE DEFINED BE_10

NON-U.S. EMPLOYEE DEFINED BENEFIT PLANS - Assumption for Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retirement Benefits [Abstract]
Discount rate	4.74%	2.24%	2.16%
Expected long-term return on plan assets	4.34%	1.79%	2.06%
Rate of compensation increase	4.02%	3.90%	2.41%

INCOME TAXES - Schedule of Inco

INCOME TAXES - Schedule of Income (Loss) Before Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Loss before income taxes:
United States	$ (5,363)	$ (84,784)	$ (29,985)
Foreign	(50,010)	(27,815)	(178,158)
Loss before income taxes	$ (55,373)	$ (112,599)	$ (208,143)

INCOME TAXES - Schedule of In_2

INCOME TAXES - Schedule of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 9,927	$ (3,582)	$ 5,033
State	2,790	2,573	1,836
Foreign	7,312	4,744	7,661
Total current	20,029	3,735	14,530
Deferred:
Federal	(10,417)	(10,333)	(38,027)
State	(1,059)	(4,045)	97
Foreign	2,280	(3,873)	(7,558)
Total deferred	(9,196)	(18,251)	(45,488)
Total	$ 10,833	$ (14,516)	$ (30,958)

INCOME TAXES - Schedule of Effe

INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
U.S. statutory income tax rate	21%	21%	21%
State income taxes, net of federal benefit	(2.10%)	1.80%	(0.70%)
Foreign income taxes	(9.90%)	(1.40%)	0.50%
Stock-based compensation	(5.40%)	(2.40%)	(0.10%)
Tax credits	7.70%	2.20%	1.60%
Uncertain tax positions	2%	1.30%	0.50%
Valuation allowance	(27.00%)	(3.80%)	2.50%
Non-deductible goodwill impairment	0%	0%	(11.70%)
Other permanent adjustments	(1.30%)	(2.60%)	0.90%
Permanent foreign exchange adjustments	(2.30%)	(1.40%)	0.50%
Other, net	(2.30%)	(1.80%)	(0.10%)
Effective income tax rate	(19.60%)	12.90%	14.90%

INCOME TAXES - Summary of Defer

INCOME TAXES - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets:
Net operating loss carryforwards	$ 398,050	$ 413,773
Capital loss carryforwards	100,061	99,505
Tax credit carryforwards	29,541	28,902
Capitalized research and development expenses	58,959	40,668
Deferred revenue	2,042	3,510
Accrued expenses	10,901	9,068
Inventory	4,108	2,820
Stock-based compensation	1,506	1,709
Fixed assets	159	2,506
Lease liabilities	12,009	12,829
Other temporary differences	440	1,324
Deferred tax assets, gross	617,776	616,614
Valuation allowance	(488,799)	(488,550)
Total deferred tax assets	128,977	128,064
Liabilities:
Intangible assets	(45,448)	(55,037)
Operating lease right-of-use assets	(8,817)	(8,519)
Interest rate swap	0	(6,168)
Unremitted foreign income	(10,567)	(8,441)
Total deferred tax liabilities	(64,832)	(78,165)
Deferred income taxes - net noncurrent assets	69,761	53,649
Deferred income taxes - net noncurrent liabilities	(5,616)	(3,750)
Total net deferred tax assets	$ 64,145	$ 49,899

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 29,500
Significant change in shareholder ownership, period of change	3 years
Significant change in shareholder ownership, benchmark percentage	50%
Deferred tax assets, valuation allowance	$ 488,799	$ 488,550
Unrecognized tax benefits, income tax penalties and interest accrued	14,000	14,900	$ 21,000
Unrecognized tax benefits that would impact effective tax rate	10,500	11,200	12,700
Unrecognized tax benefits, income tax penalties and interest expense	200	(300)	$ 1,900
Decrease in unrecognized tax benefits is reasonably possible	300
Accrued expenses and other
Operating Loss Carryforwards [Line Items]
Unrecognized tax benefits, income tax penalties and interest accrued	3,200	2,900
Edgewater
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards acquired	102,600
Annual limitation	9,700
ECI
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards acquired	23,500
Annual limitation	1,100
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	124,900
Deferred tax assets, valuation allowance	23,400	25,500
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	38,400
Israel
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	1,600,000
Foreign Tax Authority
Operating Loss Carryforwards [Line Items]
Deferred tax assets, valuation allowance	$ 465,000	$ 463,000

INCOME TAXES - Schedule of Unre

INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at January 1	$ 12,001	$ 17,813	$ 14,054
Increases related to current year tax positions	0	156	4,017
Increases related to prior period tax positions	52	40	3,168
Decreases related to the lapse of the applicable statute of limitations	(821)	(560)	(3,087)
Decreases related to prior period tax positions	(300)	(5,448)	(339)
Unrecognized tax benefits at December 31	$ 10,932	$ 12,001	$ 17,813

RELATED PARTIES (Details)

RELATED PARTIES (Details) - USD ($) $ in Thousands	12 Months Ended
RELATED PARTIES (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Total revenue	$ 826,339	$ 819,760	$ 844,957
Related Party
Related Party Transaction [Line Items]
Total revenue	$ 12,800	$ 6,600	$ 4,500

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions		12 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Sep. 19, 2022 complaint subsidiary	Dec. 31, 2023 USD ($)	Oct. 18, 2023 USD ($)	Nov. 08, 2018 executive	Dec. 31, 2017
Loss Contingencies [Line Items]
Sale of stock grant interest					100%
Maximum future unpaid royalty commitment		$ 1.3
Maximum future royalty commitment		20.4
Maximum future royalty commitment, interest		$ 0.9
Litigation liability amount			$ 4.5
Miller Complaint
Loss Contingencies [Line Items]
Number of former officers \| executive				3
Charter Complaints
Loss Contingencies [Line Items]
Loss contingency, claims filed, number \| complaint	2
Loss contingency, number of defendants \| subsidiary	2
Minimum
Loss Contingencies [Line Items]
Royalties rates					1.30%
Minimum \| LIBOR
Loss Contingencies [Line Items]
Basis spread on variable rate		1.50%
Maximum
Loss Contingencies [Line Items]
Royalties rates					5%
Maximum \| LIBOR
Loss Contingencies [Line Items]
Basis spread on variable rate		2.75%

QUARTERLY RESULTS (UNAUDITED)_2

QUARTERLY RESULTS (UNAUDITED) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 226,401	$ 203,161	$ 210,618	$ 186,159	$ 233,639	$ 207,127	$ 205,796	$ 173,198
Cost of revenue	104,693	99,658	109,148	104,757	119,626	102,809	101,246	95,143
Gross profit	121,708	103,503	101,470	81,402	114,013	104,318	104,550	78,055	$ 408,083	$ 400,936	$ 444,660
(Loss) income from operations	16,670	856	(6,622)	(35,189)	1,265	(3,296)	(7,239)	(39,054)	(24,285)	(48,324)	(117,796)
Net (loss) income	$ 7,079	$ (13,501)	$ (21,479)	$ (38,305)	$ 20,488	$ (18,416)	$ (30,180)	$ (69,975)	$ (66,206)	$ (98,083)	$ (177,185)
Loss (earnings) per share:
Basic (in dollars per share)	$ 0.04	$ (0.08)	$ (0.13)	$ (0.23)	$ 0.12	$ (0.12)	$ (0.20)	$ (0.47)	$ (0.39)	$ (0.63)	$ (1.20)
Diluted (in dollars per share)	$ 0.04	$ (0.08)	$ (0.13)	$ (0.23)	$ 0.12	$ (0.12)	$ (0.20)	$ (0.47)	$ (0.39)	$ (0.63)	$ (1.20)
Shares used in computing (loss) earnings per share:
Basic (in shares)	171,755	171,190	170,103	168,541	168,163	158,921	150,190	149,167	170,408	156,668	147,575
Diluted (in shares)	172,990	171,190	170,103	168,541	172,213	158,921	150,190	149,167	170,408	156,668	147,575