CHELMSFORD, Mass., June 13, 2005 – Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that after many years of dedicated service, Paul J. Ferri will be retiring from the Company's Board of Directors at the end of June. Mr. Ferri, the founding partner of venture capital firm Matrix Partners, has served as a director since the Company's inception in 1997.

"Since our early days as a company, Paul has added tremendous value to the Sonus Board," said Hassan Ahmed, chairman and CEO, Sonus Networks. "Sonus has benefited greatly from Paul's considerable experience in the telecommunications industry and his distinctive insights. We are grateful for his guidance over the years and thank him for his dedicated service and leadership."

In announcing his resignation, Mr. Ferri said, "I have had the pleasure of helping to build Sonus from the ground up. It has been a great honor to serve on the Sonus Board of Directors. I believe strongly in the Company's vision, and it has been a tremendously rewarding experience to be a part of its success up until this point.”

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus' voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Chelmsford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

Sonus is a registered trademark of Sonus Networks. Open Services Architecture, GSX9000 and Insignus are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.