Sonus Networks Leverages Industry Expertise As Founding Member of IMS Forum

CHELMSFORD, Mass., February 22, 2006 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that the Company will leverage its expertise as a leader in IP Multimedia Subsystem (IMS) solutions as a founding member of the IMS Forum, formerly the International Packet Communications Consortium (IPCC). The mission of the IMS Forum is to accelerate the adoption of IMS by providing an environment for discussion and resolution of real-world implementation issues, such as interoperability and standards-based architectures in the application layer.

As a founding member of IMS Forum, Sonus will collaborate with industry-leading service providers, application developers, system integrators and government agencies to help bridge the gap between the development of IMS frameworks and the creation of revenue-generating services. Sonus, which has been honored with a number of industry accolades as a result of its leadership in IMS, including Frost & Sullivan's 2006 IP Communication Carrier Infrastructure Technology Innovation & Leadership of the Year Award, brings the Forum extensive experience in the development and deployment of some of the largest VoIP networks in the world that adhere to the principles that govern today's IMS protocols. Since its inception, Sonus adopted a SIP-based distributed architecture, which is closely aligned to IMS with session control, border management, applications and management layers. The Company also founded the Open Services Partner Alliance (OSPA), the industry's largest interoperability program to develop a broad portfolio of SIP-based applications including messaging, conferencing, IP Centrex, etc.

“The universal adoption of IMS across all types of service providers and application developers around the globe provides a tremendous opportunity to reshape how we think about communications,” said Steve Edwards, Chief Marketing Officer, Sonus Networks. “Sonus has been a leading innovator in the VoIP industry and a strong advocate for standards-based interoperability. Our team has some of the deepest knowledge in the industry, and we're proud to leverage that expertise as a founding member of the IMS Forum working to promote the adoption of IMS protocols.”

“Since the Company's founding, Sonus has been focused solely on the development of carrier-class VoIP solutions, and as a founding member of the IMS Forum, Sonus' contributions will be invaluable in our efforts to promote IMS as the foundation for the next generation of communications networks,” said Michael Khalilian, chairman and president, IMS Forum.

The Sonus IMS solution builds on the proven benefits of Sonus' architecture, which supports more than 17 billion minutes of traffic per month. Key components in the Sonus IMS solution include the GSX™ family Open Services Switch (MGCF, P/I-CSCF), PSX™ Call Routing Server (BGCF), SGX™ Signaling Gateway (SGW), ASX™ Call Management Server (SIP-AS) and Insight™ Management Systems.

For additional information, see related press release entitled, “IP Communications Association Transitions to IMS Forum” or visit the IMS Forum Web site at www.IMSForum.org.

About Sonus Networks

The IMS FORUM is a global, non-profit industry association devoted to interoperable IMS services and solutions. The mission of the Forum is to accelerate the adoption of IP Multimedia Subsystems (IMS) by providing an environment for discussion and resolution of real-world implementation issues relating to interoperability, best practices, and standards-based architectures in the application layer. In addition, the Forum will provide consultancy to the industry, service providers, and vendors on best practices and approaches for IMS rollouts and interconnectivity. For additional information or to join the IMS Forum, please visit www.IMSForum.org.

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 comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus 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, dated March 15, 2005, and the “Cautionary Statements” section of Sonus' Quarterly Report on Form 10-Q, dated November 8, 2005, both 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: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the company. 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, Inc. Sonus GSX9000 Open Services Switch, PSX Call Routing Server, SGX Signaling Gateway, and the Sonus Insight Management System are trademarks of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.