Sonus Networks Collaborates with SOFTBANK Group on femtocell Demonstration

WESTFORD, Mass., June 29, 2007 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that it is collaborating in SOFTBANK Group's demonstration of femtocell technologies. In a press release issued on June 29, 2007, SOFTBANK Group announced that following the acquisition of a license for wireless spectrum from the Ministry of Internal Affairs and Communications, the Company would be demonstrating its femtocell solution.

Sonus recently announced the acquisition of privately-held Zynetix Ltd. By integrating Zynetix technology with its wireless IP network architecture, Sonus is creating leading solutions that address the end-to-end IP wireless access needs of GSM and 3G network operators worldwide. By harnessing the power of IP, Sonus Networks is helping network operators enable a new wave in communications while helping mobile operators cost-effectively deliver higher quality voice and advanced services with consumers' existing mobile phones. Sonus' advanced femtocell solution will combine an access point inside the consumer's home with the user's existing broadband network to provide an important increase in base station coverage and reducing the number of sites required for coverage. Further, by leveraging broadband connectivity, Sonus' solution will enable superior signal penetration for in-building coverage, better than with traditional mobile solutions.

In this demonstration, SOFTBANK Group is launching a comprehensive program using femtocells. In this program, SOFTBANK Group will show the benefit of leveraging a next-generation femtocell solution to connect the broadband mobile network. This demonstration will show consumers in one of the world's most technologically advanced societies that they can receive high quality mobile services without major upgrades to their in-home personal networks.

As a global leader in both the wireline and wireless market, Sonus has deployed commercial IP-Voice networks for more than 150 operators worldwide. This new solution will improve signal strength, raise overall network capacity and allow mobile operators to extend their service cost effectively, reducing the number of new cell towers needed to accommodate increased subscriber traffic, while extending overall coverage.

"SOFTBANK Group is breaking new ground in the field of telecommunications by aggressively pursuing emerging technologies to transform their business model and improve communications for their customers," said Hassan Ahmed, chairman and CEO, Sonus Networks. "We're proud that we are part of SOFTBANK Group's femtocell real world demonstration, and we share their commitment to innovation."

Sonus will be participating in the media demonstration that SOFTBANK Group is hosting in Tokyo, Japan on July 2nd, 2007. Additionally, Sonus will be hosting a media briefing on its new femtocell solution in London on July 4th.

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, whether the Company will remain listed on the NASDAQ Global Select Market and 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 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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