Ribbon Communications Inc. 10-Q

Item 5. Other Information Cybersecurity Incident Disclosure In early September 2025, the Company became aware that unauthorized persons, reportedly associated with a nation-state actor, had gained access to the Company’s IT network. The Company promptly initiated its incident response plan and began an investigation, containment and remediation effort using multiple third-party cybersecurity experts, including federal law enforcement. While the investigation is ongoing, the Company believes that it has been successful in terminating the unauthorized access by the threat actor. The Company has preliminarily determined that initial access by the threat actor may have occurred as early as December 2024, with final determinations dependent on completion of the ongoing investigation. As of the date of this quarterly report on Form 10-Q, we are not aware of evidence indicating that the threat actor accessed or exfiltrated any material information. Several customer files saved outside of the main network on two laptops do appear to have been accessed by the threat actor and those customers have been notified by the Company. As of the date of this quarterly report on Form 10-Q, the Company does not believe that the incident has had a material impact, including on its financial condition or results of operations. As noted above, the Company’s investigation into this incident is ongoing and the Company continues to take additional steps to further strengthen its network security. The Company expects to incur additional costs in the fourth quarter of 2025 associated with its continued investigation into this incident, and in network strengthening efforts, however, the Company does not currently expect such costs to be material. Insider Trading Arrangements During the three months ended September 30, 2025, none of the Company’s directors or officers (as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934) adopted , terminated or modified a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of Regulation S-K of the Securities Act of 1933). ​ ​ ​ ​ ​ 57 Table of Contents Item 6. E xhibits ​ ​ ​ ​ ​ Exhibit No. Description 2.1 ​ ​ Agreement and Plan of Merger, dated as of November 14, 2019, by and among the Registrant, Ribbon Communications Israel Ltd., Eclipse Communications Ltd., ECI Telecom Group Ltd. and ECI Holding (Hungary) Korlátolt Felelősségű Társág (incorporated by reference to Exhibit 2.1 to the Registrant’s Current Report on Form 8-K, filed November 14, 2019 with the SEC). 2.2 ​ ​ Amended and Restated Purchase Agreement, dated December 1, 2020, among Ribbon Communications Inc., Ribbon Communications Operating Company, Inc., Ribbon Communications International Limited and American Virtual Cloud Technologies, Inc. (incorporated by reference to Exhibit 2.1 to the Registrant’s Current Report on Form 8-K, filed December 7, 2020 with the SEC). 3.1 ​ ​ Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.2 to the Registrant’s Current Report on Form 8-K12B, filed October 30, 2017 with the SEC). 3.2 ​ ​ Certificate of Amendment of the Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K, filed November 28, 2017 with the SEC). 3.3 ​ ​ Certificate of Designation of Series A Preferred Stock (incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K, filed March 30, 2023 with the SEC). 3.4 ​ ​ Certificate of Amendment of the Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K, filed August 4, 2023 with the SEC). 3.5 ​ ​ Certificate of Amendment of the Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K, filed May 30, 2025 with the SEC). 3.6 ​ ​ Amended and Restated By-Laws of the Registrant (incorporated by reference to Exhibit 3.3 to the Registrant’s Annual Report on Form 10-K, filed March 8, 2018 with the SEC). 4.1 ​ ​ Ribbon Communications Inc. 2025 Incentive Award Plan (incorporated by reference to Appendix C to the Registrant’s Definitive Proxy Statement on Schedule 14A, filed April 14, 2025 with the SEC). 4.2 ​ ​ Form of Warrant (incorporated by reference to Exhibit 4.1 to the Registrant’s Current Report on Form 8-K, filed March 30, 2023 with the SEC). 31.1 * ​ Certificate of Ribbon Communications Inc. Chief Executive Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. 31.2 * ​ Certificate of Ribbon Communications Inc. Chief Financial Officer Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. 32.1 # ​ Certificate of Ribbon Communications Inc. Chief Executive Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. 32.2 # ​ Certificate of Ribbon Communications Inc. Chief Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. 101.INS * ​ Inline XBRL Instance Document 101.SCH * ​ Inline XBRL Taxonomy Extension Schema 101.CAL * ​ Inline XBRL Taxonomy Extension Calculation Linkbase 101.DEF * ​ Inline XBRL Taxonomy Extension Definition Linkbase 101.LAB * ​ Inline XBRL Taxonomy Extension Label Linkbase 101.PRE * ​ Inline XBRL Taxonomy Extension Presentation Linkbase 104 * ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101) ​ * Filed herewith. # Furnished herewith. 58 Table of Contents SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. ​ ​ ​ ​ RIBBON COMMUNICATIONS INC. ​ ​ ​ ​ ​ By: /s/ John Townsend ​ ​ John Townsend ​ ​ Executive Vice President and Chief Financial Officer ​ ​ (Principal Financial Officer) ​ ​ Date: October 23, 2025 ​ 59