WESTFORD, Mass., June 7, 1999 – Sonus Networks, an emerging leader in carrier-class packet telephony solutions, announced that it has entered into an agreement with Mitsubishi Corporation to distribute the award-winning Sonus GSX9000 and Sonus Packet Telephony Suite to the Japanese carrier market. The agreement enables Mitsubishi to further broaden its leadership in serving the carrier market by providing its customers with the industry's most scalable, reliable and open Voice-Over-Packet solutions. The Sonus GSX9000 and the Sonus Open Services Architecture^TM (OSA) will enable Mitsubishi's carrier customers to rapidly develop and deliver competitive new customer services, fueling important new revenue streams. 

Hajime Kimura, Division COO of Mitsubishi Corporation's Information Systems & Services Div.A, noted: "We have selected Sonus Networks as our distribution partner based on their unique ability to enable our customers to realize the promise of IP Telephony. Through the Sonus GSX9000 and IP Telephony Suite, we look forward to providing our carrier customers with the ability to retain and attract customers by bringing new service products to market in "Internet time." Furthermore, they will save millions of dollars in annual network operations overhead and build new services-based revenues that support their market leadership goals. Sonus delivers clear advantages over the current legacy telephony infrastructure, as well as other Voice-Over-Packet market offerings." 

Sonus President and CEO Hassan Ahmed noted: "Mitsubishi Corporation's carrier customers are among the most innovative and rapidly growing telecommunications organizations in Japan. It's market is a distinctly important one and we look forward to working closely with Mitsubishi and its customers." 

The GSX9000 is the first carrier-class Open Services Switch with the capacity, reliability and sophistication to enable the new converged PSTN/IP-based infrastructure. It is the central component of the Sonus Networks Open Services Architecture (OSA), a unique, open approach through which new services can be created easily and implemented quickly. Using the GSX9000 in the network infrastructure, the Sonus Networks OSA enables carriers to expand their network coverage and deploy new services more rapidly than with any other approach. 

The GSX900 Open Services Switch and the Sonus IP Telephony Suite were designed and developed to meet the rigorous requirements of public network service providers. These include: complete redundancy of all system elements, toll-quality voice, interoperability with the SS7 network, scalability to hundreds of thousands of calls, and NEBS compliance. Moreover, the Sonus GSX9000 and Sonus IP Telephony Suite go well beyond this base level functionality, paving the way for significant operational savings, new multi-service applications and significant incremental revenues through a new generation of customer services. 

About Sonus Networks

Sonus Networks, Inc. is delivering a new class of carrier solutions that enable the movement of telephony to converged circuit-packet networks, and the development of a new generation of innovative voice and data services. The Sonus Packet Telephony suite and Open Services Architecture^TM (OSA) cut the time-to-market for competitive new service products from years to weeks, allowing carriers and third-party developers to sustain and expand marketshare, 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, founded in 1997, is headquartered in Westford, Massachusetts and is privately held. Its management team has developed and introduced many of the industry's most widely used carrier solutions, and has led organizations such as: Ascend Communications, recently acquired by Lucent Technologies (Nasdaq: LU); Summa Four, recently acquired by Cisco Systems (Nasdaq: CSCO); Bay Networks, recently acquired by Northern Telecom (NYSE: NT); and VideoServer (Nasdaq: VSVR). 

Sonus was named one of Red Herring's "Top Ten to Watch" companies, awarded Data Communications magazine's prestigious Hot Startup of the Year and Hot Product of the Year awards, and received Technologic Partners' Investor's Choice award. Additional information is available at: http://www.sonusnet.com 

About Mitsubishi Corporation Mitsubishi Corporation ranks as one of the world's largest and most diverse enterprises. Established in April 1950, the company is based in Tokyo, Japan and has a staff of about 13,000 professionals in Japan and overseas. Clients are served through more than 50 offices in Japan and almost 200 offices and subsidiaries in other countries. Generally classified as a trading company, Mitsubishi Corporation has a wealth of experience in bringing buyers and sellers together. Through hundreds of investments in other companies, Mitsubishi Corporation is also involved in manufacturing, distribution, retailing, financing and many other activities. These diverse activities allow Mitsubishi Corporation to help determine the direction of existing markets, and to mold entirely new ones. 
Additional information is available at: http://www.mitsubishi.co.jp. 

For additional Mitsubishi Corporation information, please contact:
Katsuhiro Saito
Telecommunication System Marketing Unit
Mitsubishi Corporation
E-mail: katsuhiro.saito@jp.mitsubishicorp.com