Successful Interoperability Testing Delivers Choice To Operators To Run Queries Over IP-Based Networks

WESTFORD, Mass., July 10, 2008 – Sonus Networks, Inc. (Nasdaq: SONS), a market leader in IP communications infrastructure, today announced that VeriSign, the trusted provider of Internet infrastructure services for the networked world, has successfully demonstrated interoperability testing that will allow wireless, wireline and cable operators the ability to run number portability queries over IP-based networks.

The introduction of number portability regulation by many governments has, in some cases, increased the resources needed by carriers to complete the accurate transfer of calls. The implementation of Local Number Portability (LNP) has created the need for carriers to perform a LNP Query. This in turn has resulted in an elevated use of the carrier's SS7 networks, and in some cases necessitates the need to purchase additional SS7 network capacity.

"Minimizing cost continues to be a driving force behind the migration to IP," said Paul Florack, vice president of network and database services, VeriSign Communications Services Division. "Use of the VeriSign^® Number Identity Registry for real-time location routing number discovery leverages our ENUM infrastructure, and its complete, up-to-date, portability-corrected record of the entire North American Number Plan (NANP)."

Sonus has implemented an IP-based LNP Query mechanism, ENUM-LNP, as an inexpensive alternative to the traditional SS7-based LNP Query. The IP transported LNP Query is served by the VeriSign Number Identity Registry.

"Historically, number portability queries were taking place on traditional networks, increasing resources required to fulfill the process," commented Vikram Saksena, CTO at Sonus Networks. "By eliminating the need for legacy SS7 Service Control Points and related signaling interfaces, Sonus solutions can reduce operational costs associated with number portability implementations. We added this functionality in the most recent release of the Sonus multimedia platform and we are pleased to announce interoperability with VeriSign to enable more carriers to leverage one solution to manage their entire network, both legacy and IP-based."

Sonus' complete Local and Mobile Number Portability solutions, which are currently deployed in North America, Europe and Asia, support a variety of number portability routing methods, including traditional SS7 TCAP/INAP (Transactional Capabilities Application Part/Intelligent Network Application Part), ENUM, or direct hosting of a local number portability routing database.

About VeriSign

VeriSign, Inc. (NASDAQ: VRSN) is the trusted provider of Internet infrastructure services for the networked world. Billions of times each day, VeriSign helps companies and consumers all over the world engage in communications and commerce with confidence. Additional news and information about the company is available at www.verisign.com.

About Sonus Networks

Sonus Networks, Inc. is a market leader in IP communications infrastructure 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 for the period ended March 31, 2008, 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 restatement of its historical stock option granting practices and accounting including regulatory actions or litigation; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities and patent 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, except as required by law.

Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.

©2008 All rights reserved. VeriSign, the VeriSign logo, the checkmark circle, and other trademarks, service marks, and designs are registered or unregistered trademarks of VeriSign, Inc., and its subsidiaries in the United States and in foreign countries. All other trademarks are property of their respective owners.