Joint collaboration between Sonus Networks and HelloSoft delivers seamless handoff of Mobile Voice Over WLAN and Mobile networks

San Jose, CA October 23, 2007 – HelloSoft, Inc., a leading supplier of VoIP technologies for the converged market, and Sonus Networks (Nasdaq: SONS), a leading provider of IP-voice infrastructure solutions for wireline and wireless service providers, announced today that the two companies are joining forces to enable mobile phone users to harness the power of IP for increased flexibility and access to enriched services. The two companies are partnering together to deliver new services through a suite of converged fixed broadband and mobile wireless solutions.

By pairing HelloSoft's Voice Call Continuity (VCC) solutions with Sonus' industry leading IP Multimedia Subsystem (IMS)-based architecture, network operators can provide IP-based services to handsets leveraging a variety of access points, such as a cellular network or a wireless broadband (WLAN or WiMAX) network. For end users, this service translates into more efficient indoor coverage and improved access to multimedia services that blend voice, video and data. For network operators, the solution drives reduced operating expense for the network by leveraging an IP backbone.

"Sonus is dedicated to removing the barriers to a truly seamless communications experience," said John Nye, Vice President, Applications, Sonus Networks. "By partnering with HelloSoft, we're taking the guess work out of the equation and providing network operators with an integrated solution for delivering a world-class solution to a variety of dual-mode and multi-mode handsets."

"Working with Sonus to provide comprehensive solutions to carriers around the globe will enhance HelloSoft's IMS/VCC initiatives within the fixed-mobile convergence market," said Ron Victor, HelloSoft's General Manager of Marketing and Business Development. "Today HelloSoft has become the leading choice in VoIP and IMS/VCC Technologies for infrastructure partners."

Sonus is a recognized leader in the IP-Voice market with solutions that support wireline and wireless architectures. Carrying more than 35 billion minutes of IP voice traffic each month, Sonus' solution is one of the world's first field-proven IMS architectures deployed today in leading operators worldwide. Its applications platform, IMX, supports the rapid integration of services, including third party applications, into operators' networks. In addition to FMC solutions for dual- and multi-mode handsets, Sonus currently offers network operators the ability to expand their converged services offering through support of an end-to-end IP-based femtocell architecture.

About HelloSoft

HelloSoft is headquartered in San Jose, California with an R&D facility in Hyderabad. HelloSoft's customers include leading technology firms such as Skype, HTC, BenQ, CEC, Toshiba, Panasonic, Accton, Wistron NeWeb, NeoMagic, a la Mobile and 5V Technologies along with top semiconductor manufacturers, Original Device Manufacturers (ODMs) and Original Equipment Manufacturers (OEMs) globally. HelloSoft's partners include Texas Instruments, Intel, LongBoard, Arm, MIPS, Microsoft and Symbian. Please visit our website www.hellosoft.com for further information.

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' Quarterly Report on Form 10-Q for the period ended June 30, 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.

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.