Companies Team to Help Network Operators Realize the Promise of Convergence

WESTFORD, Mass. and ORLANDO, FL, March 29, 2007 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today at CTIA Wireless 2007 that it has formed a partnership with Apertio, a leading independent provider of subscriber-centric networks for mobile, fixed and converged telecommunications operators, to further advance the Company’s broadband-cellular convergence initiatives. The two companies will work together to bring the benefits of Sonus’ industry-leading IP Multimedia Subsystem (IMS)-ready wireless solutions with Apertio’s One-HLR, Home Location Register, a standards-based approach to a critical component of wireless networks.

Sonus is developing broadband-cellular convergence solutions designed to deliver voice service and multimedia applications that leverage new picocell and femtocell technologies, which provide localized, IP-based access to the GSM and UMTS networks. The integration of Sonus’ IMS-ready wireless architecture with the Apertio One-HLR is critical to providing a complete, end-to-end broadband-cellular converged solution. Today’s partnership announcement with Apertio is the latest in a series of initiatives designed to enhance Sonus’ broadband-cellular convergence strategy. The Company announced yesterday the acquisition of Zynetix Ltd., a provider of IP-based GSM switching solutions (see related press release, “Sonus Networks Announces Strategic Acquisition to Expand Wireless Portfolio and Capture New Market Opportunities”).  Apertio HLR is a key component of the Wireless ecosystem that Sonus is building around its newly acquired IP-MSC technology from Zynetix.  Other key elements of Sonus’ Wireless ecosystem include femto/pico cell providers ip.access, 3Way Networks and RadioFrame Networks.

“Sonus’ broadband-cellular convergence solution will bring together best-of-breed technologies to enable network operators to capitalize on new market opportunities,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “Broadband-cellular convergence is one of today’s most in-demand applications, and as a customer-centric organization, we are committed to developing a carrier-class solution with industry leaders such as Apertio that delivers on the economic benefits and service enhancements that FMC provides.”

“Broadband-cellular convergence represents an exciting new opportunity for network operators to enhance the end user experience and deliver greater operational efficiencies,” said Wallace Ascham, VP Partners, Apertio. “We’re pleased to be working hand-in-hand with Sonus to help bring an end-to-end solution to market with the quality, reliability and scalability that are the hallmark of both Sonus’ and Apertio’s solutions portfolios.”

About Apertio

Apertio is the leading independent provider of subscriber-centric networks for mobile, fixed and converged telecommunications operators. Its software application suite, Apertio One, delivers a single, open, subscriber-centric architecture for current and new generation networks. The suite includes Apertio One-NDS (Network Directory Server), Apertio One-HLR (Home Location Register) and Apertio One-HSS (Home Subscriber Server). 

The Apertio One architecture eliminates complexity and cost. It dramatically simplifies the network and places the subscriber at its heart to deliver increased revenue through rapid service deployment, and lays the foundation for convergence in networks today.

Apertio’s customers number among the world’s largest and fastest growing telecommunications operators including Orange , T-Mobile, Vodafone and AIS. The company is privately held, and headquartered in Bristol , UK , with offices in Chicago , Bangkok , Kuala Lumpur , and Beijing . For more information visit: www.apertio.com.

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 the 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.

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.