Latest Release of Sonus IMS Trunking Solution Supports Enhanced Billing Correlation between Network Operators

WESTFORD, Mass., March 8, 2007 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that the latest release of its award-winning IP Multimedia Subsystem (IMS)-ready solution now includes IMS standards-based support for billing between different service provider's IP voice networks. The latest release includes support for standards-based feature, as outlined by the 3GPP, that enables operators to track individual calls throughout their own network and when the call is handed off to other network operators. Sonus is one of the first telecommunications vendors to support this IMS required billing feature.

“As IMS has continued to evolve Sonus is committed to making sure its customers' networks are up-to-date with the latest industry standards. Having the billing infrastructure in place now is a critical pre-requisite to deploying IMS-based solutions that can successfully hand off traffic to one another,” said Vikram Saksena, Chief Technology Officer. “A typical long distance call travels across at least two different networks: a local service provider and a long distance wholesale provider, and the ability to track and bill for the call is essential. As the industry moves to the standards-based approach defined by IMS, there's an opportunity to streamline the billing process to reduce complexity and ensure the integrity of billing transactions between trusted network operators.”

The GSX™9000 Open Services Switch and the GSX™4000 Open Services Switch both support this billing requirement. Sonus' industry leading technology can generate this unique identifying information and support the seamless integration of Sonus-based networks with other IP-voice networks. In addition, Sonus' Network Border Switch delivers this functionality to allow operators to continue tracking calls for billing purposes as the call crosses network borders. This feature is critical as the world's IP-voice network continue to proliferate around the globe.

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, whether the Nasdaq Listing Council will continue the delisting stay or grant an extension or that the company's securities will remain listed on the NASDAQ Stock Market, 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.

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.