Clarent Corporation Strengthens Presence in Japan; Company Incorporates Japanese Subsidiary and Appoints New General Manager.

Business Editors/High-Tech Writers

REDWOOD CITY, Calif. and TOKYO--(BUSINESS WIRE)--April 10, 2000

Clarent(TM) Corp. (Nasdaq:CLRN), a worldwide leader in providing carrier-grade, phone-to-phone Internet Protocol (IP) telephony solutions, announced that effective today it has incorporated Clarent Japan Co., Ltd., a 100% owned Clarent subsidiary in Japan and has appointed Motoshi Sato as general manager.

With Mr. Sato's appointment and the new separate subsidiary, Clarent plans to increase its focus on the company's established customer base and on important new market opportunities in Japan.

Clarent's Japan Presence

Clarent opened its first office in Japan in late 1997 and has focused on the telecommunications service provider market there. The company has established close working relationships with three of its flagship customers in Japan:

--  JENS Corp., previously AT&T JENS, is now a subsidiary of Japan
    Telecom. JENS has built and run its AT&T @phone prepaid calling
    card service off of Clarent products since 1997. JENS Corp. also
    offers IP telephony service for international and domestic long
    distance calls to registered subscribers.

--  KDD -- Japan's largest international telecommunications service
    provider has operated Clarent-based IP telephony service offerings
    since early 1998.

--  NTT Communications Group -- Since January of 2000, the long
    distance international telecommunications arm of the world's
    largest telecommunications service provider NTT Group has provided
    global IP telephony network and clearinghouse services based on
    Clarent products.

Appointment of Motoshi Sato

Sato has been appointed as general manager, Clarent Japan Co., Ltd. He and his team are responsible for sales, local technical support, and regional marketing of Clarent's products in Japan. Prior to joining Clarent, Sato was director of business development for FORE Systems Japan, an ATM local area networking vendor. He has had extensive experience in the networking industry and his other experience includes management or country manager positions at Cabletron Systems, Digital Equipment Corp. and Banyan Systems.

"Clarent is extremely pleased to be increasing its local presence in Japan and we are very fortunate to be bringing experienced talent to the newly established subsidiary," said Mahan Wu, senior vice president and general manager, Asia Pacific, Clarent Corp. "We believe this increasing presence and the new appointment reflect Clarent's commitment to the growth potential for carrier and enterprise IP telephony business in the Japanese market."

"As the IP telephony has been implemented by telecommunications service providers in the local market, there is excellent potential ahead of us," said Motoshi Sato. "Our goal is very simple -- we want to further increase our leadership position in the VoIP market in Japan. We look forward to increasing our Japan-based business organization; channel partners; and marketing programs. I am very excited about this market opportunity."

About Clarent Corp.

Clarent Corp. is a premier provider of scalable, IP telephony products to carriers and Internet service providers around the world. Clarent's intelligent architecture and the Clarent Command Center enable Clarent products to route, manage, inter-connect and terminate high volumes of calls for service provider customers including the world's largest long distance telecommunication companies. According to an iLocus report published in 1999, more minutes travel across Clarent-enabled networks worldwide than those of any other equipment supplier.(1)

Founded in July 1996, Clarent is headquartered in Redwood City and has offices in major cities in Asia, Europe, Latin America and North America. Additional information about Clarent is available at www.clarent.com.

More Information

For more information on JENS Corp.: http://www.jens.co.jp/index_e.html

For more information on KDD: http://www.kdd.co.jp/indexe.html

For more information on NTT Communications: http://clearinghouse.ntt.com

Forward Looking Statements

This release may contain forward-looking statements regarding Clarent's products, business, customers or other factors that may affect future earnings or financial results. Such statements involve risks and uncertainties, including but not limited to potential issues relating to, inability to introduce new products, ability to retain key customers, changes in market conditions, government regulations, the international communications industry, technological changes and other factors, which could cause actual results to vary materially from those expressed in or indicated by the forward-looking statements. These risks and uncertainties are described further in the risk factors discussed in Clarent's Annual Report on Form 10-K, filed with the Securities and Exchange Commission on March 28, 2000.

Note to Editors: Clarent is a registered trademark of Clarent Corp. in the United States and other jurisdictions. All other company or product names mentioned may be trademarks or registered trademarks of the respective companies with which they are associated.

(1) "IP Telephony Clearinghouses -- A New Business Model." Published November 1999 by iLocus. iLocus, a division of Cape Saffron Ltd., is an U.K.-based research group focused on the IP telephony industry. http://www.ilocus.com