Ribbon Communications Inc. 10-Q

Item 1. Financial Statements RIBBON COMMUNICATIONS INC. Condensed Consolidated Balance Sheets (in thousands, except share and per share data) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2025 2024 Assets ​ ​ ​ ​ ​ ​ Current assets: ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 74,799 ​ $ 87,770 Restricted cash ​ ​ 1,968 ​ ​ 2,709 Accounts receivable, net ​ 218,312 ​ 254,718 Inventory ​ 80,007 ​ 79,179 Other current assets ​ 43,341 ​ 39,286 Total current assets ​ 418,427 ​ 463,662 Property and equipment, net ​ 66,427 ​ 60,364 Intangible assets, net ​ 153,752 ​ 187,537 Goodwill ​ 300,892 ​ 300,892 Deferred income taxes ​ 91,117 ​ 88,982 Operating lease right-of-use assets ​ 48,204 ​ 34,544 Other assets ​ 26,415 ​ 26,573 ​ ​ $ 1,105,234 ​ $ 1,162,554 Liabilities and Stockholders’ Equity ​ ​ Current liabilities: ​ ​ Current portion of term debt ​ $ 8,750 ​ $ 6,125 Accounts payable ​ 76,743 ​ 87,759 Accrued expenses and other ​ 88,069 ​ 106,251 Operating lease liabilities ​ 11,615 ​ 9,443 Deferred revenue ​ 106,697 ​ 119,295 Total current liabilities ​ 291,874 ​ 328,873 Long-term debt, net of current ​ 326,075 ​ 330,726 Warrant liability ​ 5,103 ​ 8,064 Operating lease liabilities, net of current ​ 61,806 ​ 37,376 Deferred revenue, net of current ​ 29,748 ​ 20,991 Deferred income taxes ​ 5,941 ​ 5,941 Other long-term liabilities ​ 24,635 ​ 25,962 Total liabilities ​ 745,182 ​ 757,933 Commitments and contingencies (Note 20) ​ ​ Stockholders’ equity: ​ ​ Common stock, $ 0.0001 par value per share; 390,000,000 shares authorized at September 30, 2025; 240,000,000 shares authorized at December 31, 2024; 176,476,492 shares issued and outstanding at September 30, 2025; 175,599,250 shares issued and outstanding at December 31, 2024 ​ 18 ​ 18 Additional paid-in capital ​ 1,975,925 ​ 1,970,708 Accumulated deficit ​ ( 1,623,614 ) ​ ( 1,574,185 ) Accumulated other comprehensive income ​ 7,723 ​ 8,080 Total stockholders’ equity ​ 360,052 ​ 404,621 ​ ​ $ 1,105,234 ​ $ 1,162,554 ​ See notes to the unaudited condensed consolidated financial statements. ​ 4 Table of Contents RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Operations (in thousands, except per share data) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Product ​ $ 109,979 ​ $ 112,151 ​ $ 307,027 ​ $ 298,894 ​ Service ​ 105,392 ​ 98,087 ​ 310,206 ​ 283,628 Total revenue ​ 215,371 ​ 210,238 ​ 617,233 ​ 582,522 Cost of revenue: ​ ​ ​ ​ ​ ​ ​ ​ Product ​ 62,037 ​ 59,405 ​ 186,676 ​ 160,044 Service ​ 40,311 ​ 34,893 ​ 115,192 ​ 103,633 Amortization of acquired technology ​ 5,057 ​ 6,323 ​ 15,722 ​ 19,406 Total cost of revenue ​ 107,405 ​ 100,621 ​ 317,590 ​ 283,083 Gross profit ​ 107,966 ​ 109,617 ​ 299,643 ​ 299,439 Operating expenses: ​ ​ ​ ​ ​ ​ ​ ​ Research and development ​ 45,894 ​ 45,645 ​ 134,158 ​ 134,897 Sales and marketing ​ 33,063 ​ 33,060 ​ 97,387 ​ 100,760 General and administrative ​ 16,368 ​ 21,588 ​ 48,126 ​ 51,680 Amortization of acquired intangible assets ​ 5,933 ​ 6,457 ​ 18,063 ​ 19,671 Acquisition-, disposal- and integration-related ​ 439 ​ — ​ 4,337 ​ — Restructuring and related ​ 3,506 ​ 3,794 ​ 10,193 ​ 8,779 Total operating expenses ​ 105,203 ​ 110,544 ​ 312,264 ​ 315,787 Income (loss) from operations ​ 2,763 ​ ( 927 ) ​ ( 12,621 ) ​ ( 16,348 ) Interest expense, net ​ ( 11,606 ) ​ ( 11,952 ) ​ ( 33,083 ) ​ ( 21,818 ) Other (expense) income, net ​ ( 134 ) ​ 1,056 ​ 836 ​ ( 15,960 ) Loss before income taxes ​ ( 8,977 ) ​ ( 11,823 ) ​ ( 44,868 ) ​ ( 54,126 ) Income tax provision ​ ( 3,132 ) ​ ( 1,599 ) ​ ( 4,561 ) ​ ( 6,473 ) Net loss ​ $ ( 12,109 ) ​ $ ( 13,422 ) ​ $ ( 49,429 ) ​ $ ( 60,599 ) ​ Loss per share: ​ ​ ​ ​ ​ Basic ​ $ ( 0.07 ) ​ $ ( 0.08 ) ​ $ ( 0.28 ) ​ $ ( 0.35 ) ​ Diluted ​ $ ( 0.07 ) ​ $ ( 0.08 ) ​ $ ( 0.28 ) ​ $ ( 0.35 ) ​ Weighted average shares used to compute loss per share: ​ ​ ​ ​ ​ Basic ​ 176,620 ​ 174,613 ​ 176,366 ​ 173,615 ​ Diluted ​ 176,620 ​ 174,613 ​ 176,366 ​ 173,615 ​ ​ See notes to the unaudited condensed consolidated financial statements. ​ 5 Table of Contents RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Comprehensive Loss (in thousands) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Net loss ​ $ ( 12,109 ) ​ $ ( 13,422 ) ​ $ ( 49,429 ) ​ $ ( 60,599 ) ​ Other comprehensive (loss) income, net of tax: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unrealized loss on interest rate swap, net of reclassifications and amortization into earnings ​ — ​ — ​ — ​ ( 6,019 ) ​ Foreign currency translation adjustments ​ ( 209 ) ​ 286 ​ ( 357 ) ​ 346 ​ Other comprehensive (loss) income, net of tax ​ ( 209 ) ​ 286 ​ ( 357 ) ​ ( 5,673 ) ​ Comprehensive loss, net of tax ​ $ ( 12,318 ) ​ $ ( 13,136 ) ​ $ ( 49,786 ) ​ $ ( 66,272 ) ​ ​ See notes to the unaudited condensed consolidated financial statements. ​ 6 Table of Contents RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Stockholders’ Equity (in thousands, except shares) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, 2025 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ other ​ Total ​ ​ Common stock ​ paid-in ​ Accumulated ​ comprehensive ​ stockholders' ​ ​ Shares Amount ​ capital ​ deficit ​ (loss) income ​ equity Balances, July 1, 2025 177,156,341 ​ $ 18 ​ $ 1,973,990 ​ $ ( 1,611,505 ) ​ $ 7,932 ​ $ 370,435 Exercise of stock options ​ 300 ​ — ​ — ​ — ​ — ​ — Exercise of warrants ​ — ​ — ​ — ​ — ​ — ​ — Repurchase of common stock ​ ( 911,092 ) ​ ​ — ​ ​ ( 3,478 ) ​ ​ — ​ ​ — ​ ​ ( 3,478 ) Vesting of restricted stock awards and units 297,586 ​ — ​ — ​ — ​ — ​ — Vesting of performance-based stock units 45,926 ​ — ​ — ​ — ​ — ​ — Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations ( 112,569 ) ​ — ​ ( 431 ) ​ — ​ — ​ ( 431 ) Stock-based compensation expense — ​ — ​ 5,844 ​ — ​ — ​ 5,844 Other comprehensive loss — ​ — ​ — ​ — ​ ( 209 ) ​ ( 209 ) Net loss — ​ — ​ — ​ ( 12,109 ) ​ — ​ ( 12,109 ) Balances, September 30, 2025 176,476,492 ​ $ 18 ​ $ 1,975,925 ​ $ ( 1,623,614 ) ​ $ 7,723 ​ $ 360,052 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, 2025 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ other Total ​ ​ Common stock ​ paid-in ​ Accumulated ​ comprehensive ​ stockholders' ​ ​ Shares Amount ​ capital ​ deficit ​ (loss) income ​ equity Balances, January 1, 2025 175,599,250 ​ $ 18 ​ $ 1,970,708 ​ $ ( 1,574,185 ) ​ $ 8,080 ​ $ 404,621 Exercise of stock options 3,997 ​ — ​ 6 ​ — ​ — ​ 6 Exercise of warrants 32,573 ​ — ​ 150 ​ — ​ — ​ 150 Repurchase of common stock ​ ( 1,483,902 ) ​ — ​ ( 5,731 ) ​ — ​ — ​ ( 5,731 ) Vesting of restricted stock awards and units 2,922,214 ​ — ​ — ​ — ​ — ​ — Vesting of performance-based stock units 423,677 ​ — ​ — ​ — ​ — ​ — Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations ( 1,021,317 ) ​ — ​ ( 3,827 ) ​ — ​ — ​ ( 3,827 ) Stock-based compensation expense — ​ — ​ 14,619 ​ — ​ — ​ 14,619 Other comprehensive loss — ​ — ​ — ​ — ​ ( 357 ) ​ ( 357 ) Net loss — ​ — ​ — ​ ( 49,429 ) ​ — ​ ( 49,429 ) Balances, September 30, 2025 176,476,492 ​ $ 18 ​ $ 1,975,925 ​ $ ( 1,623,614 ) ​ $ 7,723 ​ $ 360,052 ​ ​ See notes to the unaudited condensed consolidated financial statements. 7 Table of Contents ​ ​ RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Stockholders’ Equity (in thousands, except shares) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended September 30, 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ other Total ​ ​ Common stock ​ paid-in ​ Accumulated ​ comprehensive ​ stockholders' ​ ​ Shares Amount ​ capital ​ deficit ​ (loss) income ​ equity Balances, July 1, 2024 174,437,242 ​ $ 17 ​ $ 1,964,304 ​ $ ( 1,567,127 ) ​ $ 7,828 ​ $ 405,022 Exercise of stock options 53 ​ — ​ — ​ — ​ — ​ — Vesting of restricted stock awards and units 417,633 ​ — ​ — ​ — ​ — ​ — Vesting of performance-based stock units — ​ — ​ — ​ — ​ — ​ — Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations ( 119,130 ) ​ — ​ ( 397 ) ​ — ​ — ​ ( 397 ) Stock-based compensation expense — ​ — ​ 4,045 ​ — ​ — ​ 4,045 Other comprehensive income — ​ — ​ — ​ — ​ 286 ​ 286 Net loss — ​ — ​ — ​ ( 13,422 ) ​ — ​ ( 13,422 ) Balances, September 30, 2024 174,735,798 ​ $ 17 ​ $ 1,967,952 ​ $ ( 1,580,549 ) ​ $ 8,114 ​ $ 395,534 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accumulated ​ ​ ​ ​ ​ ​ ​ ​ ​ Additional ​ ​ ​ ​ other Total ​ Common stock ​ paid-in Accumulated ​ comprehensive ​ stockholders' ​ ​ Shares Amount ​ capital ​ deficit ​ (loss) income ​ equity Balances, January 1, 2024 172,083,667 ​ $ 17 ​ $ 1,958,909 ​ $ ( 1,519,950 ) ​ $ 13,787 ​ $ 452,763 Exercise of stock options 8,677 ​ — ​ 17 ​ — ​ — ​ 17 Vesting of restricted stock awards and units 3,444,670 ​ — ​ — ​ — ​ — ​ — Vesting of performance-based stock units 288,672 ​ — ​ — ​ — ​ — ​ — Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations ( 1,089,888 ) ​ — ​ ( 3,035 ) ​ — ​ — ​ ( 3,035 ) Stock-based compensation expense — ​ — ​ 12,061 ​ — ​ — ​ 12,061 Other comprehensive loss — ​ — ​ — ​ — ​ ( 5,673 ) ​ ( 5,673 ) Net loss — ​ — ​ — ​ ( 60,599 ) ​ — ​ ( 60,599 ) Balances, September 30, 2024 174,735,798 ​ $ 17 ​ $ 1,967,952 ​ $ ( 1,580,549 ) ​ $ 8,114 ​ $ 395,534 ​ ​ ​ ​ See notes to the unaudited condensed consolidated financial statements. 8 Table of Contents RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Cash Flows (in thousands) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2025 2024 ​ Cash flows from operating activities: ​ ​ ​ ​ ​ ​ ​ Net loss ​ $ ( 49,429 ) ​ $ ( 60,599 ) ​ Adjustments to reconcile net loss to cash flows provided by (used in) operating activities: ​ ​ ​ ​ ​ ​ ​ Depreciation and amortization of property and equipment ​ 12,182 ​ 10,131 ​ Amortization of intangible assets ​ 33,785 ​ 39,077 ​ Amortization of debt issuance costs and original issue discount ​ 2,102 ​ 4,137 ​ Amortization of accumulated other comprehensive gain related to interest rate swap ​ — ​ ( 8,196 ) ​ Stock-based compensation ​ 14,619 ​ 12,061 ​ Deferred income taxes ​ 52 ​ ( 14,614 ) ​ Change in fair value of warrant liability ​ ( 2,811 ) ​ 292 ​ Change in fair value of preferred stock liability ​ — ​ 8,091 ​ Dividends accrued on preferred stock liability ​ — ​ 2,743 ​ Payment of dividends accrued on preferred stock liability ​ ​ — ​ ​ ( 6,686 ) ​ Foreign currency exchange losses ​ 1,698 ​ 1,357 ​ Changes in operating assets and liabilities: ​ ​ ​ ​ Accounts receivable ​ 34,258 ​ 18,896 ​ Inventory ​ ( 382 ) ​ ( 1,630 ) ​ Other operating assets ​ 822 ​ 9,456 ​ Accounts payable ​ ( 5,017 ) ​ ( 7,580 ) ​ Accrued expenses and other long-term liabilities ​ ( 15,880 ) ​ 1,624 ​ Deferred revenue ​ ( 3,840 ) ​ ( 20,087 ) ​ Net cash provided by (used in) operating activities ​ 22,159 ​ ( 11,527 ) ​ Cash flows from investing activities: ​ ​ ​ ​ Purchases of property and equipment ​ ( 23,368 ) ​ ( 14,428 ) ​ Purchases of software licenses ​ — ​ ( 462 ) ​ Net cash used in investing activities ​ ( 23,368 ) ​ ( 14,890 ) ​ Cash flows from financing activities: ​ ​ ​ Borrowings under revolving line of credit ​ — ​ 44,106 ​ Principal payments on revolving line of credit ​ — ​ ( 44,106 ) ​ Proceeds from issuance of term debt ​ — ​ 342,300 ​ Principal payments of term debt ​ ( 3,938 ) ​ ( 236,270 ) ​ Payment of debt issuance costs ​ — ​ ( 5,985 ) ​ Payment of preferred stock liability ​ — ​ ​ ( 56,850 ) ​ Proceeds from the exercise of stock options ​ ​ 6 ​ 17 ​ Payment of tax obligations related to vested stock awards and units ​ ​ ( 3,827 ) ​ ​ ( 3,035 ) ​ Repurchase of common stock ​ ​ ( 5,731 ) ​ ​ — ​ Net cash (used in) provided by financing activities ​ ​ ( 13,490 ) ​ ​ 40,177 ​ Effect of exchange rate changes on cash and cash equivalents ​ 987 ​ ( 297 ) ​ Net (decrease) increase in cash and cash equivalents ​ ( 13,712 ) ​ 13,463 ​ Cash, cash equivalents and restricted cash, beginning of year ​ 90,479 ​ 26,630 ​ Cash, cash equivalents and restricted cash, end of period ​ $ 76,767 ​ $ 40,093 ​ ​ See notes to the unaudited condensed consolidated financial statements. 9 Table of Contents RIBBON COMMUNICATIONS INC. Condensed Consolidated Statements of Cash Flows (continued) (in thousands) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ ​ ​ 2025 2024 ​ Supplemental disclosure of cash flow information: ​ ​ ​ ​ ​ ​ ​ Interest paid ​ $ 28,797 ​ $ 22,851 ​ Income taxes paid ​ $ 9,565 ​ $ 12,807 ​ Income tax refunds received ​ $ 733 ​ $ 1,294 ​ Supplemental disclosure of non-cash investing activities: ​ ​ ​ ​ ​ ​ ​ Capital expenditures incurred, but not yet paid ​ $ 3,642 ​ $ 3,946 ​ Inventory transfers to property and equipment ​ $ 1,325 ​ $ 1,297 ​ Supplemental disclosure of non-cash financing activities: ​ ​ ​ ​ ​ ​ ​ Warrant liability released to additional paid-in-capital ​ $ 150 ​ $ — ​ Fair value of vested restricted and performance-based stock grants ​ $ 12,574 ​ $ 10,454 ​ ​ See notes to the unaudited condensed consolidated financial statements. ​ ​ 10 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (unaudited) ​ (1) BASIS OF PRESENTATION 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 In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting only of normal recurring items, necessary for their fair presentation with accounting principles generally accepted in the United States of America ("GAAP") and with the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). Interim results are not necessarily indicative of results for a full year or any future interim period. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 (the "Annual Report"), which was filed with the SEC on February 27, 2025. 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 The Company’s significant accounting policies are disclosed in Note 2 to the Consolidated Financial Statements included in the Annual Report. There were no material changes to the Company’s significant accounting policies during the nine months ended September 30, 2025. Principles of Consolidation The condensed consolidated financial statements include the accounts of Ribbon and its wholly-owned subsidiaries. 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 condensed consolidated financial statements include revenue recognition for arrangements that contain multiple performance obligations, inventory valuations, assumptions used to determine the fair value of stock-based compensation and the Preferred Stock and Warrants, intangible asset and 11 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ goodwill valuations, including impairments, 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. 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 condensed consolidated statements of operations, and the proceeds from the sales of receivables are included in cash from operating activities in the condensed consolidated statements of cash flows. Factoring of accounts receivable and associated fees for the three and nine months ended September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Accounts receivable sold ​ $ 40,567 ​ $ 26,635 ​ $ 95,290 ​ $ 73,597 ​ Less factoring fees ​ ​ ( 723 ) ​ ​ ( 532 ) ​ ​ ( 1,773 ) ​ ​ ( 1,466 ) ​ Net cash proceeds ​ $ 39,844 ​ $ 26,103 ​ $ 93,517 ​ $ 72,131 ​ ​ Recent Accounting Pronouncements In September 2025, the Financial Accounting Standards Board (the "FASB") issued ASU 2025-06, Intangibles- Goodwill and Other- Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”). To clarify how the accounting guidance applies to both linear and nonlinear software development, this standard removes all references to “developments stages” from ASC 350-40. ASU 2025-06 will be effective for the Company beginning with its 2028 interim and annual financial statements, with early adoption permitted as of the beginning of an annual reporting period. The Company is currently evaluating the impact of this accounting standard on its consolidated financial statements and related disclosures. In July 2025, the FASB issued ASU 2025-05, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (“ASU 2025-05”), which provides a practical expedient related to the estimation of expected credit losses for current accounts receivable and current contract assets that arise from transactions accounted for under ASC 606. In developing reasonable and supportable forecasts as part of estimating expected credit losses, all entities may elect a practical expedient that assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. ASU 2025-06 will be effective for the Company beginning with its 2026 interim and annual financial statements, with early adoption permitted. The Company believes this ASU will have no material impact on its consolidated financial statements. In November 2024, the FASB issued ASU 2024-03, Income Statement, Reporting Comprehensive Income: Expense Disaggregation Disclosures (Subtopic 220-40) (“ASU 2024-03”), which requires disaggregation of certain expense captions into specified categories in disclosures within the footnotes to the financial statements. The objective of this standard is to provide investors with information to better understand a public entity’s performance and prospects for 12 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ future cash flows, and to compare its performance over time with that of other entities. ASU 2024-03 will be effective for the Company beginning with our 2027 annual financial statements and interim financial statements thereafter, with early adoption permitted. The adoption of ASU 2024-03 will require the Company to provide new footnote disclosure about the types of expenses that are included in certain captions on its Statements of Operations, such as Cost of revenue, Research and development, Sales and marketing, and General and administrative. In December 2023, 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 with its 2025 annual financial statements. The Company expects the adoption of the standard will require certain additional income tax disclosure. ​ ​ (2) 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 earnings 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): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Weighted average shares outstanding—basic 176,620 174,613 176,366 173,615 Potential dilutive common shares — ​ — — — Weighted average shares outstanding—diluted 176,620 174,613 176,366 173,615 ​ Options to purchase the Company’s common stock and unvested restricted and performance-based stock units aggregating 14.0 million and 8.1 million shares were excluded from the computation of diluted loss per share for the three and nine months ended September 30, 2025 and 2024, respectively, because their effect would have been antidilutive. 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 11). On June 25, 2024, the Company redeemed the Preferred Stock with a portion of the proceeds from its refinancing of the 2020 Credit Facility at a rate of 103 % for a total of approximately $ 63.5 million. During the nine months ended September 30, 2025, 0.2 million Warrants were exercised. The remaining Warrants outstanding continue without modification. See Note 9 for a description of the refinancing of the 2020 Credit Facility. As of September 30, 2025 and 2024, the potential number of dilutive shares from the Warrants outstanding totaled 4.7 million and 4.9 million shares, respectively. For the three and nine months ended September 30, 2025, 0.2 million of Warrants would have been included in the calculation of diluted loss per share, but had no impact due to the Company’s net loss position. There was no impact on weighted average shares outstanding from these Warrants for three and nine 13 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ months ended September 30, 2024 as the average market 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 accrued on the Preferred Stock were not an adjustment to net income (loss) used for the calculation of diluted earnings (loss) per share as these dividends were included in the fair value adjustment of the Preferred Stock which was reflected in Other income (expense), net until the redemption of the Preferred Stock on June 25, 2024. (3) INVENTORY Inventory at September 30, 2025 and December 31, 2024 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2025 2024 On-hand assemblies and finished goods inventories ​ $ 94,204 ​ $ 95,366 Deferred cost of goods sold ​ 2,649 ​ 2,430 ​ ​ 96,853 ​ 97,796 Less noncurrent portion (included in Other assets) ​ ( 16,846 ) ​ ( 18,617 ) Current portion ​ $ 80,007 ​ $ 79,179 ​ ​ ​ (4) INTANGIBLE ASSETS AND GOODWILL The Company’s intangible assets at September 30, 2025 and December 31, 2024 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ average ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ amortization ​ ​ ​ ​ ​ ​ ​ Net ​ ​ period ​ ​ Accumulated carrying September 30, 2025 (years) ​ Cost amortization value Developed technology ​ 7.84 ​ $ 340,380 ​ $ 276,492 ​ $ 63,888 Customer relationships ​ 11.86 ​ ​ 268,140 ​ ​ 178,676 ​ ​ 89,464 Trade names ​ 3.88 ​ ​ 5,000 ​ ​ 5,000 ​ ​ — Software licenses 3.00 ​ 5,748 ​ 5,348 ​ 400 ​ ​ ​ $ 619,268 ​ $ 465,516 ​ $ 153,752 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ ​ ​ ​ average ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ amortization ​ ​ ​ ​ ​ ​ ​ Net ​ ​ period ​ ​ Accumulated carrying December 31, 2024 (years) ​ Cost amortization value Developed technology ​ 7.84 ​ $ 340,380 ​ $ 262,085 ​ $ 78,295 Customer relationships ​ 11.86 ​ ​ 268,140 ​ ​ 160,635 ​ ​ 107,505 Trade names ​ 3.88 ​ ​ 5,000 ​ ​ 4,978 ​ ​ 22 Software licenses 3.00 ​ 5,748 ​ 4,033 ​ 1,715 ​ ​ ​ $ 619,268 ​ $ 431,731 ​ $ 187,537 ​ ​ 14 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ Estimated future amortization expense for the Company’s intangible assets at September 30, 2025 was as follows (in thousands): ​ ​ ​ ​ Years ending December 31, ​ Remainder of 2025 ​ $ 10,407 2026 ​ 39,143 2027 ​ 33,979 2028 ​ 23,400 2029 ​ 18,379 2030 ​ ​ 7,722 Thereafter ​ ​ 20,722 ​ ​ $ 153,752 ​ There were no changes to the carrying value of the Company’s goodwill in the nine months ended September 30, 2025 and 2024. The components of goodwill at both September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cloud and IP Optical ​ ​ ​ ​ Edge ​ Networks ​ Total Goodwill ​ $ 392,302 ​ $ 191,996 ​ $ 584,298 Accumulated impairment losses ​ ( 167,406 ) ​ ( 116,000 ) ​ ( 283,406 ) ​ ​ $ 224,896 ​ $ 75,996 ​ $ 300,892 ​ ​ ​ (5) FAIR VALUE HIERARCHY The carrying amounts of the Company’s cash equivalents, accounts receivable, accounts payable and borrowings under a revolving credit facility in the condensed consolidated balance sheets approximate fair value due to the immediate or short-term nature of these financial instruments. Ribbon’s term debt balance as of September 30, 2025 and December 31, 2024 of $ 344.3 million and $ 348.3 million, respectively, had a fair value of approximately $ 348.6 million and $ 350.4 million, respectively. The Company’s Warrant liability had a fair value of $ 5.1 million and $ 8.1 million as of September 30, 2025 and December 31, 2024, respectively. 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 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 September 30, 2025 or December 31, 2024. ● 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, 2024, the Company determined the fair value of its defined benefit plans’ assets using Level 2 input. There were no significant changes to the Company’s defined benefit plans’ assets during the nine months ended September 30, 2025 that required the calculation of their fair value as of September 30, 2025. 15 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ ● 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. Level 3 input was used to determine the fair value of the Company’s Warrants at September 30, 2025 and December 31, 2024. The Company had no transfers between Level 2 and Level 3 fair value measurements during the three and nine months ended September 30, 2025 or 2024. (6) ACCRUED EXPENSES AND OTHER Accrued expenses at September 30, 2025 and December 31, 2024 consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2025 2024 Employee compensation and related costs ​ $ 34,601 ​ $ 44,948 Professional fees ​ 17,966 ​ 16,339 Taxes payable ​ 6,597 ​ 6,364 Other ​ 28,905 ​ 38,600 ​ ​ $ 88,069 ​ $ 106,251 ​ ​ ​ (7) WARRANTY The changes in the Company’s warranty accrual balance in the nine months ended September 30, 2025 were as follows (in thousands): ​ ​ ​ ​ Balance at January 1, 2025 $ 12,300 Current period provisions ​ 4,640 Settlements ​ ( 3,989 ) Balance at September 30, 2025 ​ $ 12,951 ​ ​ ​ At September 30, 2025, the Company’s accrual for product warranties was reflected in its condensed consolidated balance sheet as a current liability in Accrued expenses and other of $ 5.5 million, and as a long-term liability in Other long-term liabilities of $ 7.5 million. ​ (8) RESTRUCTURING AND FACILITIES CONSOLIDATION INITIATIVES The Company recorded restructuring and related expense aggregating $ 3.5 million and $ 3.8 million in the three months ended September 30, 2025 and 2024, respectively, and $ 10.2 million and $ 8.8 million in the nine months ended September 30, 2025 and 2024, 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 to 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 condensed consolidated statements of operations. Related variable lease expenses will continue to be expensed as incurred through the vacate date, at which time the 16 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 excluded from the tables below, as the liability for lease payments for each respective facility is included as a component of Operating lease liabilities in the Company’s condensed consolidated balance sheets at September 30, 2025 and December 31, 2024 (see Note 17). 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 three and nine months ended September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Severance and related costs ​ $ 2,583 ​ $ 2,289 ​ $ 4,996 ​ $ 4,264 ​ Variable and other facilities-related costs ​ 923 ​ 1,505 ​ 5,197 ​ 4,515 ​ ​ ​ $ 3,506 ​ $ 3,794 ​ $ 10,193 ​ $ 8,779 ​ ​ 2025 Restructuring Plan During the first quarter of 2025, the Company’s President and CEO approved a strategic restructuring program (as subsequently amended, the "2025 Restructuring Plan") that consists of workforce reductions in certain of the Company’s operating locations to correspond with current sales levels in those areas. The 2025 Restructuring Plan was amended in the third quarter of 2025 to reflect an increase in the scope of the proposed reductions. Any potential positions eliminated in countries outside the United States are subject to local law and consultation requirements. In connection with the 2025 Restructuring Plan, the Company recorded restructuring and related expense of $ 2.5 million and $ 5.1 million in the three and nine months ended September 30, 2025, respectively, with cash payments of $ 3.1 million in the nine months ended September 30, 2025. 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 $ 0.1 million in the three and nine months ended September 30, 2025 related to the 2023 Restructuring Plan. The Company recorded restructuring and related expense, consisting entirely of severance related costs, of $ 0.1 million and $ 2.1 million in the three and nine months ended September 30, 2024, respectively. Changes to accrued restructuring during the nine months ended September 30, 2025 and the accrued restructuring balance as of September 30, 2025 related to the 2023 Restructuring Plan were nominal. 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 17 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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. In connection with the 2022 Restructuring Plan, the Company recorded restructuring and related expense for variable and other facilities-related costs of $ 0.9 million and $ 1.5 million in the three months ended September 30, 2025 and 2024, respectively, and $ 5.2 million and $ 4.5 million in the nine months ended September 30, 2025 and 2024, respectively. A summary of the 2022 Restructuring Plan accrual activity for the nine months ended September 30, 2025 is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Initiatives ​ ​ ​ ​ ​ January 1, ​ charged to ​ Cash ​ Balance at ​ ​ 2025 ​ expense ​ payments ​ September 30, 2025 Variable and other facilities-related costs ​ $ 347 ​ 5,197 ​ ( 5,195 ) ​ $ 349 ​ Balance Sheet Classification The current portions of accrued restructuring were $ 2.3 million and $ 1.4 million at September 30, 2025 and December 31, 2024, respectively, and are included as components of Accrued expenses in the condensed consolidated balance sheets. The long-term portions of accrued restructuring are included as components of Other long-term liabilities in the condensed consolidated balance sheets. The long-term portions of accrued restructuring were $ 0.6 million and $ 0.8 million at September 30, 2025 and December 31, 2024, respectively. (9) DEBT 2024 Credit Facility On June 21, 2024, the Company entered into a Senior Secured Credit Facilities Credit Agreement (the “2024 Credit Facility” or “Credit Agreement”) as guarantor, with the Company’s wholly-owned subsidiary, Ribbon Communications Operating Company, Inc., as the borrower (the “Borrower”), HPS Investment Partners, LLC ("HPS"), as administrative agent, and HPS and WhiteHorse Capital Management, LLC ("WhiteHorse" and, together with HPS, the "Lenders"), pursuant to which the Lenders provided the Company with a $ 385 million Credit Agreement comprised of (i) a $ 350 million term loan (the “2024 Term Loan”) and (ii) a $ 35 million revolving credit facility (the “2024 Revolver”), including a $ 20 million sublimit for letters of credit. The proceeds received from the 2024 Term Loan were used to (a) repay 100 % of the amounts outstanding under the 2020 Credit Facility, (b) redeem in full the Preferred Stock and (c) pay fees and expenses related to the 2024 Credit Facility. The excess proceeds are being used by the Company for working capital and other general corporate purposes. The 2024 Term Loan and the 2024 Revolver bear interest, at the Borrower’s option, at either the Alternate Base Rate (“ABR”) or Term Secured Overnight Financing Rate ("SOFR") with an Applicable Margin for each (all as defined in the 2024 Credit Facility). Margins for the first six months were 5.25 % per annum for ABR Loans and 6.25 % per annum for SOFR Loans. Thereafter, margins vary based on the Company’s Consolidated Net Leverage Ratio, ranging from 4.75 % to 5.25 % per annum for ABR Loans and 5.75 % to 6.25 % per annum for SOFR Loans. The 2024 Term Loan and the 2024 Revolver will both mature on June 21, 2029. The 2024 Term Loan is being repaid in equal quarterly installments: approximately $ 0.9 million beginning with the third quarter of 2024 through the second quarter of 2025; approximately $ 2.2 million beginning with the third quarter of 2025 and ending with the second quarter of 2027; and approximately $ 4.4 million quarterly thereafter, with the remaining principal balance of approximately $ 298.4 million due on the maturity date of June 21, 2029. In connection with the establishment of the 2024 Credit Facility, $ 7.7 million of original issue discount was withheld by the Lenders, and the Company incurred $ 6.3 million of debt issuance costs for a total of $ 14.0 million that is being amortized to Interest expense, net over the term of the 2024 Credit Facility. 18 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ The 2024 Credit Facility requires compliance with a Maximum Consolidated Net Leverage Ratio (the "Financial Covenant"), as defined in the 2024 Credit Facility, which is tested on a quarterly basis. The Company was in compliance with the Financial Covenant as of September 30, 2025 and December 31, 2024. The indebtedness and other obligations under the 2024 Credit Facility are irrevocably and unconditionally guaranteed on a joint and several basis by the Company and its subsidiaries (together, the "Guarantors"). The 2024 Credit Facility is secured on a first-priority basis by liens on substantially all assets of the Borrower and the Guarantors. 2020 Credit Facility On June 21, 2024, the Company used the proceeds from the 2024 Credit Facility to, among other things, repay all amounts outstanding under its Senior Secured Credit Facilities Credit Agreement, dated March 3, 2020 (as amended, the "2020 Credit Facility"), by and among the Company, as a guarantor, Ribbon Communications Operating Company, Inc., as the borrower (the "Borrower"), Citizens Bank, N.A., Santander Bank, N.A., and others as lenders ("2020 Credit Facility Lenders"). The Company wrote off $ 2.0 million of debt issuance costs in conjunction with the early extinguishment of the 2020 Credit Facility. The 2020 Credit Facility had a maturity date of March 2025 and originally provided for $ 500 million of commitments from the 2020 Credit Facility 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 was available for swingline loans. The Company entered into the Sixth Amendment to the 2020 Credit Facility (the “Sixth Amendment”) effective March 30, 2023. Among other things, 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. Also, the Sixth Amendment replaced LIBOR with SOFR as the alternative rate available to the Company for calculating interest owed under the 2020 Credit Facility with the margin fixed at 4.5 %. Debt issuance costs associated with the Sixth Amendment totaled $ 1.7 million and were being amortized on a straight-line basis over the remaining life of the 2020 Credit Facility and were written off in conjunction with the early extinguishment of the 2020 Credit Facility on June 21, 2024. 19 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ The Company had the following outstanding borrowings, unamortized debt issuance costs and original issue discount, letters of credit, interest rates, and remaining borrowing capacity under the 2024 Credit Facility as of September 30, 2025 and December 31, 2024: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ ​ December 31, ​ ​ 2025 ​ 2024 Current portion of Term Debt ​ $ 8,750 ​ $ 6,125 ​ ​ ​ ​ ​ ​ ​ ​ ​ Long-term Debt, net of Current: ​ ​ ​ ​ ​ ​ ​ Long-term Debt, net of Current (Face Amount) ​ $ 335,562 ​ $ 342,125 ​ Original Issue Discount ​ ​ ( 5,211 ) ​ ​ ( 6,261 ) ​ Unamortized Debt Issuance Costs - Contra-Liability ​ ( 4,276 ) ​ ( 5,138 ) ​ Long-term Debt, net of Current ​ $ 326,075 ​ $ 330,726 ​ ​ ​ ​ ​ ​ ​ ​ ​ Total Face Amount of Borrowings ​ $ 344,312 ​ $ 348,250 ​ ​ ​ ​ ​ ​ ​ ​ ​ Unamortized Original Issue Discount and Debt Issuance Costs: ​ ​ ​ ​ ​ Other Assets ​ $ 944 ​ $ 1,134 ​ Long-Term Debt - Contra Liability ​ 9,487 ​ 11,399 ​ Total Unamortized Original Issue Discount and Debt Issuance Costs ​ $ 10,431 ​ $ 12,533 ​ ​ ​ ​ ​ ​ ​ ​ ​ Remaining Borrowing Capacity ​ $ 35,000 ​ $ 35,000 ​ ​ ​ ​ ​ ​ ​ ​ ​ Average Interest Rates: ​ ​ ​ ​ ​ ​ ​ Term Loan ​ 10.6 % 10.6 % ​ The Company’s debt maturities as of September 30, 2025 were as follows: ​ ​ ​ ​ Years ending December 31, ​ ​ Remainder of 2025 ​ $ 2,187 2026 ​ ​ 8,750 2027 ​ ​ 13,125 2028 ​ ​ 17,500 2029 ​ 302,750 ​ $ 344,312 ​ Letters of Credit and Other Guarantees In the course of its business, the Company uses letters of credit, bank guarantees, and surety bonds (collectively, "Guarantees"). The Company had $ 11.1 million and $ 10.9 million of Guarantees under various uncommitted facilities as of September 30, 2025 and December 31, 2024, respectively. The Company had no letters of credit outstanding under the 2024 Credit Facility as of September 30, 2025 or December 31, 2024. At September 30, 2025 and December 31, 2024, the Company had cash collateral of $ 2.0 million and $ 2.7 million supporting the Guarantees, respectively, which are reported as Restricted cash in the Company’s condensed consolidated balance sheets. (10) 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 20 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 2024 Term Loan Facility had outstanding balances of $ 344.3 million and $ 348.3 million at September 30, 2025 and December 31, 2024, respectively. The 2024 Revolving Credit Facility was undrawn at September 30, 2025 and December 31, 2024. Borrowings under the 2024 Credit Facility and the 2020 Credit Facility have variable interest rates based on SOFR (see Note 9). As a result of exposure to interest rate movements, the Company entered into an interest rate swap arrangement in March 2020 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. In two separate transactions during 2022, the Company sold a total of $ 60 million of the notional amount of its interest rate swap back to its counterparty for $ 3.1 million, reducing the notional amount of this swap to $ 340 million. The gain in Accumulated other comprehensive (loss) income related to these sales totaled $ 3.1 million and was 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 $ 0.2 million and $ 0.4 million in three and nine months ended September 30, 2024, respectively. The remaining unamortized gain in Accumulated other comprehensive (loss) income of approximately $ 0.5 million was written off to interest expense in conjunction with the refinancing of the 2020 Credit Facility on June 21, 2024. In two separate transactions in 2023, the Company received a total of $ 19.2 million, consisting of $ 0.8 million of interest and $ 18.4 million for the sale of the remaining $ 340 million notional amount of its swap. The portion of the gain in Accumulated other comprehensive (loss) income related to the term loan debt prepaid on the date of the final sale of the swap totaled $ 7.3 million and was released into earnings immediately as Other expense, net. The portion of the gain in Accumulated other comprehensive (loss) income related to the remaining term loan debt balance totaled $ 12.0 million and was being released into earnings on a straight-line basis over the remaining term of the 2020 Credit Facility as a decrease to interest expense beginning in the second quarter of 2023, the amortization of which was $ 1.4 million and $ 3.0 million for three and nine months ended September 30, 2024, respectively. The remaining unamortized gain in Accumulated other comprehensive (loss) income of $ 4.4 million was written off to interest expense in conjunction with the refinancing of the 2020 Credit Facility on June 21, 2024. 21 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 these objectives, 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 related 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 condensed consolidated balance sheet and is subsequently reclassified into earnings in the period that the hedged forecasted transactions affect earnings. Any ineffective portion of the change in the fair value of the derivative would have been recognized directly in earnings. However, there was no hedge ineffectiveness recorded over the life of the swap. 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 condensed consolidated statements of comprehensive (loss) income for the nine months ended September 30, 2024 was a reclassification of $ 6.0 million to increase interest expense. The Company had no derivative assets or liabilities at September 30, 2025 or December 31, 2024. (11) 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. On June 25, 2024, the Company redeemed the Preferred Stock with a portion of the proceeds from the refinancing of the 2020 Credit Facility at a rate of 103 % for a total of approximately $ 63.5 million. During the nine months ended September 30, 2025, 0.2 million Warrants were exercised. The remaining Warrants outstanding continue without modification. See Note 9 for a description of the refinancing of the 2020 Credit Facility. The Company accounted for the Preferred Stock until it was redeemed and continues to account for the remaining 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 considered 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 was calculated quarterly through March 31, 2024 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 quarterly using the Black-Scholes Pricing Model. Changes in the fair value of the Preferred Stock and the Warrants are reported as Other expense, net in the Company’s condensed consolidated statements of operations. The Company determined the fair value of the Warrants using Level 3 input. The key assumptions into the model utilized were as follows as of September 30, 2025 and December 31, 2024: ​ 22 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ ​ ​ December 31, ​ ​ 2025 ​ 2024 Stock price ​ $ 3.80 ​ ​ $ 4.16 ​ Strike price ​ $ 3.77 ​ ​ $ 3.77 ​ Risk-free rate ​ 3.64 % ​ 4.21 % Volatility ​ 55.1 % ​ 57.5 % Dividend yield ​ 0.0 % ​ 0.0 % Time to expiration (years) ​ 1.5 ​ ​ 2.2 ​ Fair value of Warrant per share ​ $ 1.09 ​ ​ $ 1.66 ​ ​ The changes in the Company’s Preferred Stock liabilities for the nine months ended September 30, 2024 were as follows (in thousands): ​ ​ ​ ​ ​ Preferred stock ​ ​ liability Balance at January 1, 2024 ​ $ 53,337 Payable in-kind dividends ​ 2,743 Reversal of fair value adjustments ​ 5,605 Call premium ( 3 %) ​ 1,851 Redemption (June 25, 2024) ​ ​ ( 63,536 ) Balance at September 30, 2024 ​ $ — ​ The changes in the Company’s Warrant liabilities for the nine months ended September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ Nine months ended September 30, ​ ​ 2025 ​ 2024 Balance at beginning of year ​ $ 8,064 ​ $ 5,295 Exercise of warrants ​ ​ ( 150 ) ​ ​ — Fair value change ​ ( 2,811 ) ​ 292 Balance at end of period ​ $ 5,103 ​ $ 5,587 ​ The Preferred Stock, redeemed on June 25, 2024, was subordinate to the Company’s indebtedness and senior to the Company’s common stock or other equity. Holders of the Preferred Stock were entitled to cumulative dividends that accrued quarterly. Dividends were payable in-kind during the first year at a rate of 9.25 %. At the Company’s option, the dividends were payable in-kind or in cash during the second year at a rate of 9.75 %. Dividends thereafter were to be 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 was 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. 23 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ During the nine months ended September 30, 2025, 176,658 of the Warrants were exercised in cashless exercises, resulting in the issuance of 32,573 of the Company’s common stock at a weighted average fair value of $ 4.62 per share. There were 4,681,432 remaining Warrants outstanding as of September 30, 2025. (12) REVENUE RECOGNITION The Company derives revenue from two primary sources: products and services. Product revenue includes: 1) the Company’s proprietary hardware and software that function together to deliver the products’ essential functionality and 2) the Company’s software only solutions that can be used on either the Company’s hardware or third-party hardware. Both proprietary hardware and software only solutions 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 (“SSP”). The Company’s software licenses typically provide a perpetual right to use the Company’s software. However, 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 from sales of the Company’s perpetual and term-based software licenses is typically recognized 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 term-based software licenses at the start of the renewal period. Revenue related to sales of SaaS-based software is recognized ratably over the service period as the customer does not take possession of the software or have the ability to take possession of the software. 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. Service 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 24 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 and to recognize revenue because it believes such method, in general, best depicts the transfer of assets to its customers. The input method measures costs the Company has incurred in the period for its contracts. In some infrequent instances, the Company may engage a third-party to perform services on its behalf and in those cases the output method is used to recognize revenue because it best depicts the transfer of assets to its customers. Under the output method, there is a 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 can 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, typically over a period of one to five days . Payment terms for the Company’s contracts with its customers typically range from 30 to 60 days from the invoice date. In certain cases, the Company may offer extended payment terms, which are assessed on a case-by-case basis. ​ The Company does not generally offer significant financing components in its contracts with customers. However, if a contract includes a significant financing component, the transaction price is adjusted for the time value of money. For the three and nine months ended September 30, 2025, the impact of financing components was immaterial. ​ Amounts billed to customers for sales and other taxes are excluded from the transaction price. Revenue is recognized net of any taxes collected from customers, which are subsequently remitted to government authorities. ​ 25 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ The Company’s typical performance obligations include the following: ​ ​ ​ ​ ​ ​ ​ When Performance Obligation is Typically ​ Performance Obligation ​ Satisfied ​ When Payment is Typically Due Software and Product Revenue ​ ​ ​ ​ Software licenses (perpetual or term) For perpetual licenses, typically when made available for download (point in time); for term-based licenses, at the beginning of the specified term (point in time) Generally, within 30-60 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 30-60 days of invoicing Hardware When control of the hardware passes to the customer; typically, upon delivery (point in time) Generally, within 30-60 days of invoicing Software upgrades Upon transfer of control; typically, when made available for download (point in time) Generally, within 30-60 days of invoicing Customer Support Revenue Customer support Ratably over the course of the support contract (over time) Generally, within 30-60 days of invoicing Professional Services Other professional services (excluding training services) As work is performed (over time), typically on the input method based on hours incurred Generally, within 30-60 days of invoicing (upon completion of services) Training As the training is delivered (over time), typically one to five days Generally, within 30-60 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 SSP for each distinct performance obligation. The Company typically has more than one 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. 26 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 three and nine months ended September 30, 2025 and 2024 was disaggregated geographically as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service revenue ​ ​ ​ ​ Product ​ Service revenue ​ (professional ​ ​ ​ Three months ended September 30, 2025 ​ revenue ​ (maintenance) ​ services) ​ Total revenue United States ​ $ 39,515 ​ $ 35,191 ​ $ 21,967 ​ $ 96,673 Europe, Middle East and Africa ​ ​ 35,765 ​ ​ 18,045 ​ ​ 9,082 ​ ​ 62,892 Asia Pacific ​ ​ 30,337 ​ ​ 9,723 ​ ​ 3,191 ​ ​ 43,251 Other ​ ​ 4,362 ​ ​ 6,556 ​ ​ 1,637 ​ ​ 12,555 ​ ​ $ 109,979 ​ $ 69,515 ​ $ 35,877 ​ $ 215,371 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service revenue ​ ​ ​ ​ Product ​ Service revenue ​ (professional ​ ​ ​ Three months ended September 30, 2024 ​ revenue ​ (maintenance) ​ services) ​ Total revenue United States ​ $ 58,198 ​ $ 33,670 ​ $ 17,690 ​ $ 109,558 Europe, Middle East and Africa ​ 24,708 ​ 17,918 ​ 7,141 ​ 49,767 Asia Pacific ​ 25,590 ​ 10,262 ​ 2,388 ​ 38,240 Other ​ 3,655 ​ 7,169 ​ 1,849 ​ 12,673 ​ ​ $ 112,151 ​ $ 69,019 ​ $ 29,068 ​ $ 210,238 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service revenue ​ ​ ​ ​ Product ​ Service revenue ​ (professional ​ ​ ​ Nine months ended September 30, 2025 ​ revenue ​ (maintenance) ​ services) ​ Total revenue United States ​ $ 127,957 ​ $ 102,061 ​ $ 65,572 ​ $ 295,590 Europe, Middle East and Africa ​ 80,759 ​ ​ 53,790 ​ ​ 25,955 ​ 160,504 Asia Pacific ​ 89,342 ​ ​ 28,831 ​ ​ 10,009 ​ 128,182 Other ​ 8,969 ​ ​ 19,552 ​ ​ 4,436 ​ 32,957 ​ ​ $ 307,027 ​ $ 204,234 ​ $ 105,972 ​ $ 617,233 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service revenue ​ ​ ​ ​ Product ​ Service revenue ​ (professional ​ ​ ​ Nine months ended September 30, 2024 ​ revenue ​ (maintenance) ​ services) ​ Total revenue United States ​ $ 120,173 ​ $ 99,156 ​ $ 42,812 ​ $ 262,141 Europe, Middle East and Africa ​ 99,636 ​ 53,105 ​ 23,027 ​ 175,768 Asia Pacific ​ 68,304 ​ 30,262 ​ 7,912 ​ 106,478 Other ​ 10,781 ​ 22,397 ​ 4,957 ​ 38,135 ​ ​ $ 298,894 ​ $ 204,920 ​ $ 78,708 ​ $ 582,522 ​ The Company’s product revenue from its direct sales program and from indirect sales through its channel partner program for the three and nine months ended September 30, 2025 and 2024 was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Indirect sales through channel partner program ​ $ 28,488 ​ $ 38,000 ​ $ 90,211 ​ $ 114,958 ​ Direct sales ​ 81,491 ​ 74,151 ​ 216,816 ​ 183,936 ​ ​ ​ $ 109,979 ​ $ 112,151 ​ $ 307,027 ​ $ 298,894 ​ 27 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ ​ The Company’s product revenue from sales to enterprise customers and from sales to service provider customers for the three and nine months ended September 30, 2025 and 2024 was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Sales to enterprise customers ​ $ 37,467 ​ $ 40,002 ​ $ 99,751 ​ $ 115,912 ​ Sales to service provider customers ​ 72,512 ​ 72,149 ​ 207,276 ​ 182,982 ​ ​ ​ $ 109,979 ​ $ 112,151 ​ $ 307,027 ​ $ 298,894 ​ ​ The Company’s product revenue and service revenue components by segment for the three and nine months ended September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Product revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cloud and Edge $ 46,097 $ 53,455 $ 134,070 $ 124,554 IP Optical Networks ​ 63,882 ​ 58,696 ​ 172,957 ​ 174,340 Total product revenue $ 109,979 $ 112,151 $ 307,027 $ 298,894 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service revenue: ​ ​ ​ ​ Maintenance: ​ ​ ​ ​ Cloud and Edge $ 52,315 $ 53,595 $ 154,899 $ 159,454 IP Optical Networks ​ 17,200 ​ 15,424 ​ 49,335 ​ 45,466 Total maintenance revenue ​ 69,515 ​ 69,019 ​ 204,234 ​ 204,920 Professional services: ​ ​ ​ ​ Cloud and Edge ​ 26,026 ​ 21,028 ​ 80,108 ​ 56,294 IP Optical Networks ​ 9,851 ​ 8,040 ​ 25,864 ​ 22,414 Total professional services revenue ​ 35,877 ​ 29,068 ​ 105,972 ​ 78,708 Total service revenue $ 105,392 $ 98,087 $ 310,206 $ 283,628 ​ 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 condensed 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. 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 condensed 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 nine months ended September 30, 2025 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 28 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 condensed consolidated balance sheets. The changes in the Company’s accounts receivable, unbilled receivables and deferred revenue balances for the nine months ended September 30, 2025 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Unbilled ​ Deferred ​ Deferred ​ ​ Accounts ​ accounts ​ revenue ​ revenue ​ receivable receivable (current) (long-term) Balance at January 1, 2025 ​ $ 176,575 ​ $ 78,143 ​ $ 119,295 ​ $ 20,991 Increase (decrease), net ​ ( 22,861 ) ​ ( 13,545 ) ​ ( 12,598 ) ​ 8,757 Balance at September 30, 2025 ​ $ 153,714 ​ $ 64,598 ​ $ 106,697 ​ $ 29,748 ​ The Company recognized approximately $ 96 million of revenue in the nine months ended September 30, 2025 that was recorded as deferred revenue at December 31, 2024 and approximately $ 95 million of revenue in the nine months ended September 30, 2024 that was recorded as deferred revenue at December 31, 2023. Of the Company’s deferred revenue reported as long-term in its condensed consolidated balance sheet at September 30, 2025, the Company expects that approximately $ 10 million will be recognized as revenue in 2026 , approximately $ 8 million will be recognized as revenue in 2027 and approximately $ 12 million will be recognized as revenue in 2028 and beyond. The Company applies the optional exemption of not disclosing the transaction price allocated to the remaining performance obligation for its contracts with an original duration of less than one year. In 2024, the Company entered into a contract with an existing customer that has revenue allocated to remaining performance obligations, which includes unearned revenue and amounts that will be invoiced and recognized as revenue in future periods of approximately $ 204 million and $ 285 million as of September 30, 2025 and December 31, 2024, respectively. At this time, the Company expects to recognize the majority of the revenue related to this contract in the years 2025 through 2028. 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 condensed 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. These costs have been deferred on our condensed consolidated balance sheet and are being amortized over the expected life of the customer contract, which is generally five years . At September 30, 2025 and December 31, 2024, the Company had $ 2.1 million and $ 2.8 million of deferred sales commissions capitalized, respectively. (13) OPERATING SEGMENT INFORMATION The Company has two operating and reportable segments, Cloud and Edge and IP Optical Networks, that align with the way the business is managed. The Company’s CODM, its President and Chief Executive Officer, makes key operating decisions and assesses performance based upon these reportable segments. ​ 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 29 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 primarily of its Session Border Controller ("SBC") products and its 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 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 does not provide 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 expenses 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 adjusted gross profit to evaluate each segment's performance. The Company calculates adjusted gross profit by excluding from cost of revenue both amortization of acquired technology and stock-based compensation and may also exclude other items in future periods that the Company believes are not part of the Company's core business. The Company uses adjusted gross profit to develop its annual budget and quarterly forecasts. The CODM analyzes adjusted gross profit compared to the annual budget and quarterly forecasts to allocate resources. Ribbon’s calculation of adjusted gross profit may not be comparable to similarly titled measures used by other companies. See below for a reconciliation of segment adjusted gross profit to gross profit and loss before income taxes. ​ The tables below present significant segment expenses regularly reviewed by the CODM for the three and nine months ended September 30, 2025 and 2024 (in thousands): ​ 30 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Segment revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cloud and Edge $ 124,438 $ 128,078 $ 369,077 $ 340,302 IP Optical Networks ​ 90,933 ​ 82,160 ​ 248,156 ​ 242,220 Revenue $ 215,371 $ 210,238 $ 617,233 $ 582,522 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Segment adjusted gross profit: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cloud and Edge $ 77,387 $ 86,661 $ 229,537 $ 226,726 IP Optical Networks ​ 35,805 ​ 29,634 ​ 86,580 ​ 93,390 Total segment adjusted gross profit ​ 113,192 ​ 116,295 ​ 316,117 ​ 320,116 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reconciliation of segment adjusted gross profit to gross profit and loss before income taxes ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock-based compensation expense ​ ​ ( 169 ) ​ ​ ( 355 ) ​ ​ ( 752 ) ​ ​ ( 1,271 ) ​ Amortization of acquired technology ​ ( 5,057 ) ​ ( 6,323 ) ​ ( 15,722 ) ​ ( 19,406 ) Gross profit ​ 107,966 ​ 109,617 ​ 299,643 ​ 299,439 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development expense ​ ​ 45,894 ​ ​ 45,645 ​ ​ 134,158 ​ ​ 134,897 ​ Sales and marketing expense ​ ​ 33,063 ​ ​ 33,060 ​ ​ 97,387 ​ ​ 100,760 ​ General and administrative expense ​ ​ 16,368 ​ ​ 21,588 ​ ​ 48,126 ​ ​ 51,680 ​ Amortization of acquired intangible assets ​ ​ 5,933 ​ ​ 6,457 ​ ​ 18,063 ​ ​ 19,671 ​ Acquisition-, disposal- and integration-related expense ​ ​ 439 ​ ​ — ​ ​ 4,337 ​ ​ — ​ Restructuring and related expense ​ ​ 3,506 ​ ​ 3,794 ​ ​ 10,193 ​ ​ 8,779 ​ Interest expense, net ​ ​ 11,606 ​ ​ 11,952 ​ ​ 33,083 ​ ​ 21,818 ​ Other expense (income), net ​ ​ 134 ​ ​ ( 1,056 ) ​ ​ ( 836 ) ​ ​ 15,960 ​ Loss before income taxes ​ $ ( 8,977 ) ​ $ ( 11,823 ) ​ $ ( 44,868 ) ​ $ ( 54,126 ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Segment depreciation expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cloud and Edge $ 2,399 $ 2,324 $ 7,151 $ 6,981 IP Optical Networks ​ 2,026 ​ 1,037 ​ 5,031 ​ 3,150 Depreciation expense $ 4,425 $ 3,361 $ 12,182 $ 10,131 ​ ​ ​ ​ 31 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ (14) MAJOR CUSTOMERS The following customers contributed 10% or more of the Company’s revenue in the three and nine months ended September 30, 2025 and 2024: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ ​ 2025 2024 2025 2024 Verizon Communications Inc. ​ 18 % 15 % 18 % 13 % ​ Bharti Telecom Limited ​ 10 % * ​ * ​ * ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ * Less than 10% of total revenue ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2025 and December 31, 2024, 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. (15) COMMON STOCK REPURCHASES ​ In the second quarter of 2025, the Company's Board of Directors approved a program to repurchase up to $ 50 million of the Company’s common stock (the “2025 Repurchase Program” or the “Repurchase Program”). Commencing on June 5, 2025 and continuing through December 31, 2027, the Repurchase Program is being funded with cash on hand or cash generated from operations. During the three and nine months ended September 30, 2025, the Company used $ 3.5 million and $ 5.7 million, respectively, including transaction fees, to repurchase and retire 0.9 million and 1.5 million shares of its common stock, respectively, under the Repurchase Program, with $ 44.3 million remaining for future repurchases as of September 30, 2025. (16) 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 2025 Incentive Award Plan (the “2025 Plan”) which provides for the award of stock options, stock appreciation rights ("SARs"), restricted stock awards ("RSAs"), performance-based stock awards ("PSAs"), restricted stock units ("RSUs"), performance-based stock units ("PSUs") and other stock- or cash-based awards. The 2025 Plan, approved by the Company’s stockholders at the annual meeting held on May 28, 2025 (the “2025 Annual Meeting”), permits the Company to grant awards of up to (i) 14 million new shares of its common stock, plus (ii) 2,180,307 shares of its common stock previously reserved for issuance by the Company’s Amended and Restated 2019 Incentive Award Plan plus that number of shares of its common stock subject to awards granted under certain prior plans which become available for grant under the 2025 Plan. At the 2025 Annual Meeting, the Company's stockholders also approved an amendment to the Company’s Restated Certificate of Incorporation, as amended, to increase the number of authorized shares of its common stock by 150 million shares to a total of 390 million shares. Executive Equity Arrangements 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 32 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ from one to three years . PSUs granted consist of 60 % that have both performance and service conditions (the "Performance PSUs") and 40 % that have both market and service conditions (the "Market PSUs"). Each Performance PSU is comprised of three consecutive fiscal year performance periods beginning in the year of grant, with one -third of the Performance PSUs attributable to each fiscal year performance period. The Market PSUs have one three-year performance period, beginning January 1 in the year of grant and ending on December 31, three years thereafter. The number of shares of common stock underlying the PSUs that can be earned will not exceed 200 % of the Performance or Market PSUs. Shares subject to PSUs that fail to be earned will be forfeited. Restricted Stock Units The activity related to the Company’s RSUs for the nine months ended September 30, 2025 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ Shares ​ Fair Value Unvested balance at January 1, 2025 3,997,108 ​ $ 3.04 Granted 8,304,705 ​ $ 3.67 Vested ( 2,922,214 ) ​ $ 3.09 Forfeited ( 205,197 ) ​ $ 3.49 Unvested balance at September 30, 2025 9,174,402 ​ $ 3.58 ​ The total grant date fair value of shares of restricted stock underlying RSUs that vested during the nine months ended September 30, 2025 was $ 9.0 million. Performance-Based Stock Units The activity related to the Company’s PSUs for the nine months ended September 30, 2025 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Average ​ ​ ​ ​ Grant Date ​ ​ Shares ​ Fair Value Unvested balance at January 1, 2025 3,605,892 ​ $ 3.75 Granted 2,118,290 ​ $ 4.02 Vested ( 423,677 ) ​ $ 3.52 Forfeited ( 461,794 ) ​ $ 3.53 Unvested balance at September 30, 2025 4,838,711 ​ $ 3.91 ​ The total grant date fair value of shares of restricted stock underlying PSUs that vested during the nine months ended September 30, 2025 was $ 1.5 million. 33 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ Stock-Based Compensation The condensed consolidated statements of operations include stock-based compensation for the three and nine months ended September 30, 2025 and 2024 as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Product cost of revenue ​ $ 17 $ 64 $ 116 $ 234 ​ Service cost of revenue ​ 152 ​ 291 ​ 636 ​ 1,037 Research and development ​ 398 ​ ​ 745 ​ ​ 1,578 ​ ​ 2,429 Sales and marketing ​ ​ 1,493 ​ ​ 1,108 ​ ​ 3,732 ​ ​ 3,219 ​ General and administrative ​ ​ 3,784 ​ ​ 1,837 ​ ​ 8,557 ​ ​ 5,142 ​ ​ ​ $ 5,844 $ 4,045 $ 14,619 $ 12,061 ​ ​ At September 30, 2025, there was $ 32.8 million, net of expected forfeitures, of unrecognized stock-based compensation expense related to unvested RSUs and PSUs. This expense is expected to be recognized over a weighted average period of approximately two years . (17) LEASES The Company has operating leases for corporate offices and research and development facilities. Operating leases are reported separately in the Company’s condensed 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 September 30, 2025 and December 31, 2024 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. Lease contracts may contain variable lease costs, such as common area maintenance, utilities and tax 34 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ 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 may accelerate the amortization of those lease assets through the planned cease-use date of each facility, resulting in additional amortization expense. No such accelerated amortization was recorded in the three and nine months ended September 30, 2025 or 2024. The Company did no t record estimated future variable lease costs in the three and nine months ended September 30, 2025 or 2024 related to the 2022 Restructuring Plan. All incremental accelerated amortization and accruals for estimated future variable costs are included in Restructuring and related expense in the Company’s condensed consolidated statements of operations. At September 30, 2025 and December 31, 2024, the Company had accruals of $ 0.9 million and $ 1.1 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. The Company leases its corporate offices and other facilities under operating leases, which expire at various times through 2036. The Company’s right-of-use lease assets and lease liabilities at September 30, 2025 and December 31, 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ Classification 2025 2024 Assets: ​ ​ ​ Operating lease assets ​ Operating lease right-of-use assets ​ $ 48,204 ​ $ 34,544 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities: ​ ​ ​ ​ Current Operating ​ Operating lease liabilities ​ $ 11,615 ​ $ 9,443 ​ Non-Current Operating ​ Operating lease liabilities, net of current ​ 61,806 ​ 37,376 ​ Total Operating lease liabilities ​ ​ ​ $ 73,421 ​ $ 46,819 ​ ​ The components of lease expense for the three and nine months ended September 30, 2025 and 2024 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ September 30, ​ September 30, ​ September 30, ​ September 30, ​ ​ 2025 2024 2025 2024 Operating lease cost* ​ $ 3,742 ​ $ 4,165 ​ $ 10,564 ​ $ 12,471 Short-term lease cost ​ 3,499 ​ 3,362 ​ 10,579 ​ 10,216 Variable lease costs (costs excluded from minimum fixed lease payments)** ​ 1,620 ​ 814 ​ 3,359 ​ 2,497 Sublease income ​ ( 29 ) ​ ( 209 ) ​ ( 245 ) ​ ( 686 ) Net lease cost ​ $ 8,832 ​ $ 8,132 ​ $ 24,257 ​ $ 24,498 * No accelerated amortization was recorded in the three and nine months ended September 30, 2025 or 2024. ** No variable lease costs were expensed in the three and nine months ended September 30, 2025 or 2024 for future estimated variable expenses related to certain assets partially or fully vacated with no intent or ability to sublease. 35 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ Cash flows related to the Company’s leases included in the measurement of operating lease liabilities were classified as operating cash flows and totaled $ 12.0 million and $ 14.0 million in the nine months ended September 30, 2025 and 2024, respectively. The Company’s non-cash investing and financing activities in the nine months ended September 30, 2025 and 2024 related to the addition of operating leases resulted in right-of-use assets (“ROUs”) obtained in exchange for lease obligations of $ 20.3 million and $ 2.1 million, respectively, and operating lease liabilities recorded of $ 31.0 million and $ 2.1 million, respectively. Other information related to the Company’s leases as of September 30, 2025 and December 31, 2024 was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2025 2024 Weighted average remaining lease term (years): ​ Operating leases 7.02 5.35 ​ Weighted average discount rate: ​ ​ Operating leases 9.46 % 7.73 % ​ Future minimum fixed lease payments under noncancelable leases at September 30, 2025 were as follows (in thousands): ​ ​ ​ ​ ​ Operating ​ ​ leases Remainder of 2025 ​ $ 4,565 2026 ​ 17,777 2027 ​ 16,525 2028 ​ 13,729 2029 ​ 11,393 2030 and beyond ​ 38,847 Total lease payments ​ 102,836 Less: interest ​ ( 29,415 ) Present value of lease liabilities ​ $ 73,421 ​ ​ (18) INCOME TAXES The Company recorded income tax provisions of $ 4.6 million and $ 6.5 million in the nine months ended September 30, 2025 and 2024, respectively. These amounts reflect the Company’s estimates of the effective rates expected to be applicable for the respective full years, adjusted for any discrete events, which are recorded in the period in which they occur. These estimates are reevaluated each quarter based on the Company’s estimated tax expense for the full fiscal year. The estimated effective tax rate includes the impact of valuation allowances in various jurisdictions. The Company intends to continue to maintain a valuation allowance on its deferred tax assets until there is sufficient evidence to support the reversal of all or some portion of the respective allowances. The One Big Beautiful Bill Act (the "Act") was signed into law on July 4, 2025. The Act reinstates bonus depreciation, allows for full expensing of R&D expenses, and increases the limitation of interest deductibility for 2025, amongst many other provisions. Since the Act became law during the third quarter of 2025, we accounted for the effects of the Act on our tax provision in the three months ended September 30, 2025. The most significant impact of the Act for us is the ability to deduct the unamortized balance of capitalized R&D costs. 36 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ ​ (19) RELATED PARTIES The Company recognized revenue from its largest stockholder of $ 1.0 million and $ 1.4 million in the three months ended September 30, 2025 and 2024, respectively, and $ 4.0 million and $ 4.4 million in the nine months ended September 30, 2025 and 2024, respectively. Also, the Company’s accounts receivable from its largest stockholder totaled $ 3.8 million and $ 5.5 million as of September 30, 2025 and December 31, 2024, respectively. In addition, certain related party stockholders participated in the Private Placement described in Note 11. (20) COMMITMENTS AND CONTINGENCIES Contingencies Liabilities for Royalty Payments to the IIA Prior to the Company’s acquisition of ECI Telecom Group Ltd. ("ECI"), ECI had received research and development grants from the Office of the Innovation Authority of the Israeli Ministry of Economics (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 effective through 2023, interest was calculated at the higher of LIBOR plus 1.5 % to 2.75 %. For grants approved in 2024 and thereafter, interest is calculated based on SOFR. At September 30, 2025, the Company had $ 2.0 million of unpaid royalties accrued. The Company’s maximum possible future royalties commitment at September 30, 2025 of $ 13.0 million, including interest of $ 0.9 million, was based upon estimates of future sales of product and services and the grants received from the IIA not yet repaid. 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 currently unable 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. 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. On May 14, 2025, the Delaware court granted our dispositive motion for summary judgement and denied Charter’s motion for partial summary judgement. The Delaware court’s ruling ended the case in Delaware at the trial level. Charter has appealed the 37 Table of Contents RIBBON COMMUNICATIONS INC. Notes to Condensed Consolidated Financial Statements (Continued) (unaudited) ​ Delaware court’s ruling and oral argument on the appeals is scheduled for December 10, 2025. Discovery remains on-going in the New York case. No trial date has been set for the case in New York. ​ ​ 38 Table of Contents