Latest Release of IMS-Ready Trunking Solution Allows Consumers to Choose Their Favorite Japanese Operator

WESTFORD, Mass., January 24, 2007 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that with the latest release of its award-winning IP Multimedia Subsystem (IMS)-ready core infrastructure solutions, the Sonus platform now supports the newly standardized method to provide both Local Number Portability (LNP) and Mobile Number Portability (MNP) services for Japanese network operators. Under recent regulation, LNP service with the new method will start by NTT and many other Japanese network operators from February 2007, which will enable Japanese consumers to select their preferred network provider, while keeping their existing phone number. With more than a 75% market share position in Japan, according to Synergy Research Group, Sonus allows operators to comply with this new regulation through a software upgrade.

“LNP and MNP are critical to allowing consumers to choose their provider and to creating a healthy, competitive market for network operators. Sonus Networks is committed to helping operators in the region comply with the new legislation seamlessly and efficiently,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “The ability to change providers while retaining your existing phone number is an important driver for innovation, and consumers now have the flexibility to pick the type of service that's tailored to their specific needs.”

Sonus Networks is the leading provider of next generation voice solutions in Japan. Many of Sonus' customers throughout the region are deploying the latest version of Sonus' core trunking solution in order to comply with the new regulation. With this software upgrade, Sonus' core trunking solution supports all methods of Japanese LNP and MNP with an onboard database and number translation features that are applicable to all carrier types.

"The promise of LNP and MNP is undeniable. Removing a major roadblock to switching providers gives operators an important weapon in the battle for consumer acquisition and retention. It gives them a better opportunity to actually sell their competitive differentiators," said Peter Jarich, Principal analyst for Wireless Infrastructure with Current Analysis. "By most accounts, Sonus has a dominant position in Japan. With Sonus' support of LNP and MNP, Japanese consumers are positioned to reap the benefits."

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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