Seasoned Technology Industry Veteran Joins Board as Independent Director

CHELMSFORD, Mass., September 13, 2004 – Sonus Networks (Nasdsaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that it has appointed John P. Cunningham to its Board of Directors. He has an extensive history in executive leadership roles throughout his 28-year tenure at IBM, followed by a distinguished career as chief financial officer at a number of leading companies including the Maytag Corporation, Whirlpool Corporation, Wang Global, and most recently, Citrix Systems.

“Sonus is committed to the highest and most rigorous financial standards, and John’s impeccable track record is exactly the type of experience we’re looking to add to help us meet those goals,” said Hassan Ahmed, chairman and chief executive officer, Sonus Networks. “John possesses the right blend of financial expertise and technology acumen needed to bring Sonus through its next phase of development, and he is a truly welcome addition to our board of directors.”

“With voice over IP technology on the brink of wide-scale carrier adoption, this is a very exciting time to be joining the market leader,” said Cunningham. “Sonus has a distinguished customer roster and innovative technology solutions, and is positioned to be a driving force in transforming the world’s telecommunications networks to VoIP. I’m looking forward to the chance to help guide the company along that path.” Cunningham, an “audit committee financial expert” as defined by the rules of the Securities Exchange Commission, will serve as the chairman of the Audit Committee for Sonus’ Board of Directors.

In addition to Sonus, Cunningham presently serves on the Board of privately held Smart Disk Corporation and has previously held positions on the Boards of Directors of MSL Corporation, Baltimore Technologies, Pinnacle Bank of Michigan and Manhattanville College.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice over IP (VoIP) infrastructure solutions for wireline and wireless service providers. With its Open Services ArchitectureTM (OSA), 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.

This release may contain forward-looking statements regarding future events that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. Readers are referred to the “Risk Factors” section of Sonus’ Annual Report on Form 10-K/A dated July 28, 2004 and filed with the SEC, and the “Cautionary Statements” section of Sonus’ Quarterly Report on Form 10-Q, dated August 20, 2004 and filed with the SEC, which identify important risk factors that could cause actual results to differ from those contained in the forward-looking statements. In addition, any forward-looking statements represent Sonus’ views only as of today and should not be relied upon as representing Sonus’ views as of any subsequent date. While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so.

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