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Strategic Appointment to Strengthen Partner Alliances and Drive New Business Initiatives

SWINDON, UK, September 15, 2004 - Sonus Networks (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, today announced the appointment of Tim Ward as senior director of partner management and business development for Europe, Middle East and Africa (EMEA). Ward will target key systems integrators and build new partner alliances to drive the adoption of VoIP technology in EMEA.

Ward has over 20 years experience in the telecommunications industry and a successful history of developing strategic relationships with key network service providers, systems integrators and channel partners. Prior to joining Sonus, Ward acted as vice president, Europe at Sylantro Systems where he was responsible for building relationships with major vendors such as Alcatel, Siemens and IBM. Previous to Sylantro, Ward was also managing director at LongBoard Ltd, a developer of carrier voice applications, where he was responsible for building relationships with network service providers and setting up the EMEA channel.

“Sonus is committed to extending its leadership position in the service provider VoIP market and the appointment of Tim will enable us to explore many new opportunities in EMEA,” commented Steve Edwards, chief marketing officer and general manager, EMEA, Sonus Networks. “Tim has an excellent understanding of the telecoms market and his experience of building relationships with key industry leaders will have a positive impact on our business.”

“2004 is already proving to be an important year in the move to IP, as carriers begin to replace the PSTN with VoIP technology,” said Ward. “This is an exciting time to join the company that is leading the migration to VoIP, as Sonus looks to build on its existing relationships and create new strategic partnerships.”

About Sonus Networks

Sonus Networks, Inc. is a leading provider of packet voice 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, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus’ award-winning 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. For more information, visit 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.