Sonus Networks NXTcomm BOOTH #4215

IMS Forum® Plugfest II Showcases Sonus' Ability to Deliver IMS-Based Services in Multivendor Environments

WESTFORD, Mass., and CHICAGO, IL, June 19, 2007 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today at NXTcomm 2007 (Booth#4215), one of North America's largest communications industry trade shows, that it has successfully completed a battery of tests designed to validate the Company's IP Multimedia Subsystem (IMS)-based solutions. Sonus was one of 18 vendors that participated at the IMS Forum Plugfest II, hosted by the IMS Forum (www.IMSForum.org) and held at the University of New Hampshire InterOperability Lab in Durham, N.H., and successfully deployed a fully-functional, end-to-end IMS network running multimedia applications. 

Among the highlights of Plugfest II, Sonus successfully demonstrated its IMS-based Broadband-Mobile Convergence (BMC) solutions, leveraging its IMX® Multimedia Applications Platform, an IMS-compliant SIP application server, and integrating successfully with solutions from multiple other vendors, including presence-based applications, such as instant messaging and SMS. Sonus was the only BMC application server to participate in the testing.

"There has been a lot of buzz about the promise of IMS, but it isn't until the hype translates into real-word applications and services that consumers will want that network operators will begin to seriously look at evolving their network architecture plans," said Vikram Saksena, chief technology officer, Sonus Networks. "The IMS Forum's Plugfest II was our latest opportunity to demonstrate to the industry at large that Sonus' IMS solutions are real today, and Sonus customers have a distinct advantage when it comes to the evolution of IMS, because from day one, our solutions have embraced the same principles that are the very foundation of IMS."

"Sonus was a critical player in Plugfest II, providing many of the critical elements in an IMS architecture and demonstrating that IMS-based applications are a reality today," said Michael Khalilian, IMS Forum Chairman & President. "The IMS Forum's Plugfests provide companies with a recurring opportunity to test their implementations in real world multi-vendor environment and provides a valuable resource as commercial IMS deployments are now starting to occur."

Plugfest II focused mainly on IMS applications and call flows. In addition to its IMX platform and Broadband-Mobile Convergence solution, Sonus IMS core components comprising of the HSX, Home Subscriber Server (HSS) and the SRX, which includes the Call Session Control Functions (S-CSCF), were used in all test cases. Sonus also provided the IMS-compliant PSTN interworking solution, including the Sonus' GSX^™ Open Services Switch for Media Gateway Control Function/Media Gateway (MGCF/MGW), the SGX^™ Signaling Gateway, and the PSX^™ Breakout Gateway Control Function (BGCF) as part of the Broadband-Mobile convergence solution. 

The Sonus IMS-based solution tested at the Plugfest is the same platform currently available for deployment in customer networks today. The solution provides multiple real-world benefits in the immediate-term, such as its sophisticated traffic management and routing policies, while providing the foundation needed to support the development of future IMS-enabled services and applications.

Sonus will be showing a video documentary of the IMS Plugfest in Booth #4215 and IMS Forum Booth #3669 at NXTcomm, June 19-21st. Additional information on Plugfest II and future events can be found at www.IMSForum.org. 

About the IMS Forum

The IMS Forum® is a global, non-profit industry association devoted to interoperable IP Multimedia Subsystems services and solutions. IMS Forum's mission is to accelerate the interoperability of IMS applications and services, enabling enterprise and residential consumers to quickly benefit from the delivery of quadruple play voice, video, internet and mobile services over broadband via cable, wireless and fixed networks. The IMS Forum is the creator and organizer of the IMS Plugfest^™, the industry's only event focused on IMS services interoperability verification and certification.

Through its organized Plugfests, working group interaction, and other activities, forum members are able to develop cost-effective technical frameworks for converged IP services over wireline, cable, 3G, WiFi and WiMAX networks. Plugfest II was held June 4-8, 2007, at the University of New Hampshire InterOperability Lab in Durham, N.H. Plugfest II results will be released in Chicago at NXTcomm, June 18-21, 2007, at the IMS Forum's booth #3669. For additional information or to join the IMS Forum and the IMS Plugfests, 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 Westford, 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 Item 1A "Risk Factors" of Sonus' Quarterly Report on Form 10-Q dated May 8, 2006, filed with the SEC, which identifies 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 and uncertainties associated with the Company's announced review of its historical stock option grants and accounting, including any potential impact on the Company's financial statements or results, any tax liabilities or penalties, the Company's inability to timely report with the Securities and Exchange Commission, the Company's potential inability to meet NASDAQ requirements for continued listing, potential investigations, regulatory actions or litigation arising out of the review or any restatement; 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.

The product information in this press release is for informational purposes only and is subject to change at Sonus' sole discretion without notice. Sonus has no obligation or commitment to develop or deliver any future release, upgrade, feature, enhancement or function described in this release. The information is provided "AS IS," with all faults, and without any warranties whatsoever, express or implied, including, but not limited to, warranties of merchantability, performance, or fitness for a particular purpose.

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