CHELMSFORD, Mass., September 10, 2004 – Sonus Networks (Pink Sheets: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced that it has received a determination from The Nasdaq Listing Qualifications Panel that it is appropriate to relist Sonus’ common stock on The Nasdaq National Market. Nasdaq has informed Sonus that its common stock will again trade on The Nasdaq National Market upon the opening of the market on Monday, September 13, 2004, under the symbol “SONS.”

“We are excited to return to The Nasdaq National Market,” said Hassan Ahmed, chairman and chief executive officer, Sonus Networks. “With our relisting on Nasdaq, we close out this difficult chapter in Sonus’ history, and we are extremely grateful for the continued support of Sonus’ shareholders, customers and employees throughout this period. Looking ahead, we are enthusiastic about the voice over IP market and the opportunities ahead of us.”

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. Risk factors include, among others, risks associated with the pending securities litigation and SEC investigation. 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.