Ribbon Communications Inc. Commitments Disclosure

(26) COMMITMENTS AND CONTINGENCIES

Contingencies

Liabilities for Royalty Payments to the IIA

Prior to the ECI Acquisition, ECI had received research and development grants from the IIA. The Company assumed ECI’s contract with the IIA, which requires the Company to pay royalties to the IIA on proceeds from the sale of products which the Israeli government has supported by way of research and development grants. The royalties for grants prior to 2017 were calculated at the rates of 1.3% to 5.0% of the aggregated proceeds from the sale of such products developed at certain of the Company’s R&D centers, up to an amount not exceeding 100% of such grants plus interest at LIBOR. Effective for grants approved in 2017 and 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 December 31, 2025, the Company had $1.4 million of unpaid royalties accrued. The Company’s maximum possible future royalties commitment at December 31, 2025 of $11.3 million, including interest of $0.8 million, was based upon estimates of future sales of products 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. Charter appealed the Delaware court’s decision, but on December 18, 2025, the Delaware Supreme Court affirmed the lower court’s judgment. This ended the case in Delaware. No trial date has been set for the case in New York.

WideOpenWest Complaint. On August 9, 2023, WideOpenWest, Inc. and WideOpenWest Finance, LLC (collectively, “WOW”) filed a complaint against Ribbon alleging breach of contract with respect to indemnification obligations purportedly owed to WOW in connection with WOW’s legal dispute with Sprint Communications Company L.P., which was settled by WOW in the second quarter of 2023. The complaint was filed in the 429th Judicial District of the District Court of the State of Texas, in Collin County, Texas and has since been transferred to the 493rd Judicial District Court in Collin County. In the complaint, WOW is seeking monetary damages. The Company filed its answer to the complaint on October 5, 2023. On October 14, 2024, the Company and WOW agreed to settle this matter. In connection with the settlement, the Company will pay WOW a total of $5.0 million, with $2.0 million paid at the time of settlement and the remaining $3.0 million paid over the next 18-months in equal quarterly installments.