Sonus Networks and ip.access Deliver Fixed Mobile Convergence

Sonus Networks and ip.access Make One Number, One Voicemail, One Call A Reality At CTIA 2008

Westford, MA., and Las Vegas, NV., April 1, 2008 – Sonus Networks, Inc. (Nasdaq: SONS), the market leader in IP voice infrastructure, and ip.access, the market leader in femtocell and picocell infrastructure solutions are answering the demands of mobile subscribers for an integrated approach to voice communication, opening up new revenue opportunities for both mobile and wireline operators through fixed mobile convergence.

At CTIA 2008, Sonus Networks and ip.access will be demonstrating a complete broadband mobile convergence solution that combines the Sonus mobilEdge™ Wireless Access Node with ip.access’ Oyster 3G™ femtocells and nanoGSM® 2G picocells. The solution integrates cellphones into enterprise communications systems for business customers, and supports innovative "connected home" features for home users. The complete network will be shown live at this year's CTIA conference in Las Vegas, USA, Booth #3439. Visitors to Sonus Networks' booth will experience first-hand wireless calls through ip.access picocells and femtocells via the mobilEdge SIP/IP core network, including Find-Me-Follow-Me and Extension Dialing services for enterprise picocell applications.

"We now offer a complete solution that allows users to experience a new level of communication services. By leveraging existing broadband, carriers can supply high capacity bandwidth services, realizing the promise of triple play services onto the wireless handset," said Vikram Saksena, chief technology officer, Sonus Networks. "Together with ip.access, we are helping network operators streamline the delivery of advanced multimedia services, providing an improved communication experience for enterprise customers."

"A robust wireless network requires the seamless interoperability of carrier-class, high performance solutions," said Stephen Mallinson, CEO of ip.access. "By integrating Sonus' mobilEdge Wireless Access Node with our Oyster 3G and nanoGSM indoor radio solutions, we can provide network operators with a fully distributed network architecture that delivers valuable new services to existing handsets."

Sonus Networks and ip.access have partnered in order to ensure that their technology is integrated and interoperable. By deploying the complete, standards-based network solution, mobile operators can now offer residential and business customers the full power of indoor mobile coverage over existing handset and broadband connections, seamless handover to the macro-mobile network, and a complete suite of residential or business value added services.

"This solution blends fixed and mobile services into a seamless experience for the end user. Wireless carriers can now offer fully integrated services to business users as well as unlimited long distance wireless services to residential users. We are taking the guesswork involved with interoperability out of the equation," concluded Saksena.

The solution is available to customers today. More information is available at www,sonusnet.com and www.ipaccess.com.

About ip.access

Based in Cambridge, UK, ip.access ltd (www.ipaccess.com) is a leading manufacturer of cost-effective picocell and femtocell infrastructure solutions for GSM, GPRS, EDGE and 3G. These solutions bring IP and cellular technologies together and solve in-building access problems for mobile operators, opening up new revenue streams while defending existing business.

ip.access is the company behind the Oyster 3G™ femtocell, winner of numerous industry awards including the Best Radio Access Product at the 2007 Global Mobile Awards. The Oyster 3G dramatically increases 3G cell capacity and coverage; improves quality of experience; and drives down costs. Oyster 3G is ready for today's mobile networks and tomorrow’s IMS infrastructure.

The ip.access nanoGSM® is the world's most deployed picocell solution for cellular networks. It provides GSM, GPRS and EDGE coverage and capacity for offices, shops and using satellite backhaul passenger aircraft, ships and in remote rural areas.

With more than 30 live networks around the world and many more being deployed, ip.access is the partner of choice for operators competing in the new converged marketplace.

ip.access counts Scottish Equity Partners, Rothschild Gestion, Intel Capital, Amadeus Capital Partners, ADC, Cisco and Motorola Ventures among its shareholders.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of IP-voice 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' Annual Report on Form 10-K for the period ended December 31, 2007, 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 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.

The 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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