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Next-Generation Japanese Carrier Develops Largest Nationwide, Converged IP Network; After First Month of Service, Network Supports More Than 360,000 Subscribers

TOKYO, Japan, and WESTFORD, Mass., May 15, 2001 – Sonus Networks (Nasdaq: SONS) today announced that Fusion Communications has deployed Sonus' voice infrastructure solutions as the foundation of their next-generation voice network, which began delivering live traffic last month. Sonus is supplying Fusion a full range of packet voice solutions under a multi-million dollar, multiyear relationship. 

"We have built a highly sophisticated and efficient network that leverages the most innovative network architecture and solutions," stated Tadahisa Sumida, president and CEO, Fusion Communications Corp. "We thoroughly evaluated the solutions available today and found that only Sonus' products met our requirements for scalability, performance and reliability. Sonus' family of voice infrastructure solutions not only enabled us to reduce the cost and time involved in building our network, but have also allowed us to quickly deliver revenue-generating voice and data services."

Fusion was established in March 2000 with the mission of becoming Japan's first and premier IP-centric telecommunications carrier, providing services to business and domestic phone users in Japan. Utilizing advanced packet technologies, Fusion has rapidly developed the largest nationwide VoIP network and is Japan's first carrier to support the integrated transmission of voice and data.

Working together with Sonus and its distribution partner, Nissho Electronics, a leading network integrator in Japan, Fusion implemented Japanese versions of Sonus' award-winning GSX900^(TM) Open Services Switch, PSX6000^(TM) SoftSwitch and SGX2000^(TM) SS7 Signaling Gateway throughout its network. Initially, Fusion has rolled out the Sonus systems in 17 cities across Japan, with plans to rapidly build out a network footprint that will encompass all major cities and population centers. Launched just last month, the Fusion network already supports more than 360,000 subscribers.

By deploying Sonus' Open Services Architecture^(TM) (OSA) and voice infrastructure solutions throughout its fiber-optic network, Fusion will be delivering to its customers a full complement of traditional voice services such as long distance telephone service, international telephone service, VPN and virtual ISP. Additionally, Fusion plans to offer a range of innovative, enhanced voice over packet services including IP phone connectivity and unified communications, among others. In the second phase of the network, with the construction of a high-speed broadband fiber-optic backbone, Fusion plans to provide an environment that will enable rich multi-media broadband content services.

"We are extremely pleased to be working with Fusion in this tremendously exciting endeavor, the development of Japan's first national packet voice network," said Hassan Ahmed, Sonus' president and CEO. "With their aggressive buildout plans, Fusion is setting the standard for other carriers in Japan and is revolutionizing the communications landscape. By equipping itself with world-class technology, Fusion is positioned to become a world-class player."

About Fusion Communications Corp.

Fusion Communications Corporation is a next-generation Japanese telecommunications carrier focusing on IP technology. Fusion was founded in March 2000 and began services on April 1, 2001. Their mission is to create a world-class, high-quality, cost-effective telecommunications environment in Japan. Starting with a nationwide IP network which they have single-handedly built, they are progressing toward the global trend of an integrated IP telecommunications infrastructure which brings down the cost of various telecommunications services such as voice, data, internet access and converged service applications.

In July 2000 Fusion obtained a "Type-1 Telecommunications Carrier License" and a license for "Fixed Wire Access - FWA", and in addition, they have been given a carrier identification number. Fusion's first service offering, which went live on April 1, 2001, was the nationwide "0038" long distance service. This Fusion service represents a first in Japan, as this service is not dependent on distance. Existing carriers in Japan services are dependent on distance. Fusion is the first carrier with a uniform rate nationwide at 20 yen per three minutes at all times of the day. Fusion has also been registered as a carrier under the "My Line/My Line Plus" carrier selection service in Japan, which began on May 1, 2001.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of voice infrastructure products for the new public network. Sonus' solutions enable service providers to deploy an integrated network capable of carrying both voice and data traffic, and to deliver a range of innovative, new services. The Sonus Open Services ArchitectureTM (OSA) and award-winning Packet Telephony suite cut the time-to-market for competitive new service products, allowing carriers and third-party developers to expand market share and build important new revenue streams. Its highly scalable products fully interoperate with and extend the life and utility of today's public network. Sonus embodies in its management and staff decades of experience in developing carrier-class voice, data and multimedia solutions for implementation in the world's largest networks. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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 Sonus' Annual Report on Form 10-K, dated March 28, 2001, filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. These risk factors include, among others, the Company's ability to grow its customer base, dependence on new product offerings, market acceptance of its products, rapid technological and market change, integration risks relating to the acquisition of telecom technologies and manufacturing and sourcing risks.

GSX9000, PSX6000, SGX2000 and Open Services Architecture are trademarks of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.