Sonus Networks Developing Solution for Network Operators to Extend the Benefits of IMS to Today's GSM Mobile Handsets

WESTFORD, Mass. and BARCELONA, Spain, February 13, 2007 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today at the 3GSM World Congress in Barcelona, Spain that the Company is developing a suite of products that will unleash new business opportunities for mobile communications providers. Sonus is creating end-to-end solutions designed to deliver voice service and multimedia applications that leverage new Low Powered GSM (LP GSM) picocell and femtocell technologies. The solution is particularly beneficial to network operators in regions where regulators have released new wireless licenses designed to put unused or under-used spectrum into the market.

This technology will result in better in-building coverage through the use of picocells and femtocells that when combined with Sonus' IP Multimedia Subsystem (IMS)-based architecture, dramatically reduces the costs for traffic backhaul. Research by Unstrung (“3G Home Base Stations”, Unstrung Insider, Volume 6, no. 1) estimates that by leveraging a VoIP infrastructure as part of a complete LP GSM solution, backhaul costs can be reduced from approximately $50 Euro per subscriber to approximately $20 Euro per subscriber. Equally as important, this new suite of products will provide a seamless migration path to a complete IMS architecture, which will allow consumers to customize their personal voice services, regardless of their physical location.

“The world is moving to a wireless environment. The dynamics governing the communications industry are changing quickly, and to be successful, network operators need a technology partner that will help them to adapt and capitalize on new opportunities,” said Hassan Ahmed, chairman and CEO. “Today's consumers want the ability to move seamlessly between their homes and offices, and they are demanding the ability to customize services while on the go. Regulators in Europe are responding to this increasing demand with the release of additional spectrum that will enable network operators to deliver these ubiquitous services. Sonus is committed to helping our customers seize this opportunity and deliver real-time applications that redefine traditional voice services.”

In April 2006, the Office of Communications (Ofcom) in the United Kingdom was the first to release new wireless licenses into the market. With the release of this additional spectrum, network operators are able to move beyond traditional radio access networks (RANs) to also provide fixed and wireless broadband services. With the development of Sonus' new product portfolio, network operators, including operators that have traditionally only offered wireline services, will be able to bridge the mobile and fixed-line networks to deliver a seamless user experience.

“Fixed-to-Mobile applications have captured the attention of network operators around the world. In the UK, the release of the additional spectrum creates an ideal path for making these applications reality,” said Vikram Saksena, chief technology officer, Sonus Networks. “The benefits are highly compelling, both in terms of streamlining cost infrastructure and delivering enhanced services to end users, and Sonus is committed to partnering with our customers to deliver a state-of-the-art network that leverages the additional spectrum release.”

With more than 2 billion subscribers, over 80% of the world's mobile network users operate on GSM spectrum. The release of this additional GSM spectrum enables network operators to provide wider wireless coverage and improved voice quality where factors such as a building's physical structure degrades cellular signals. This performance is achieved while optimizing the cost and control of the operator's access network by taking advantage of existing broadband infrastructure, which results in more efficient use of traditional mobile spectrum. Additionally, network operators will benefit from a cost efficient approach to routing wireless network traffic and service delivery as their customers shift their usage from fixed to mobile networks. Consumers benefit from a more cost-efficient, seamless communications experience and gain the ability to access customizable next generation services.

“Femtocells have great potential for providing low-cost in-building coverage,” says Gabriel Brown, Chief Analyst with Unstrung Insider. “One of the decisions operators deploying this technology face is how to perform call control and integrate with mobile core networks, enterprise telephony systems, and the PSTN. There are several options under evaluation, with the target architecture expected to be based around SIP/IMS.”

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.