Clarent Exhibits Award-Winning IP Telephony Solutions at Telexpo and Latin America Telecom 2000.

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Business Editors/High-Tech Writers

Telexpo 2000

SAO PAULO, Brazil--(BUSINESS WIRE)--March 28, 2000

Clarent(TM) Corporation (Nasdaq:CLRN), a worldwide leader in providing carrier-grade, phone-to-phone Internet Protocol (IP) telephony solutions, today announced plans to exhibit at Telexpo (Green Pavilion stand No. 246) Sao Paulo, March 28 - March 31, and at Latin America Telecom 2000 in Rio de Janeiro, April 10 - April 15 (Hall 3 USA/33).

Sidnei Stifelmann, vice president and general manager, Clarent Latin America, and a team of Clarent telecommunications specialists are expected to be available at both shows to present and discuss the Clarent IP telephony solutions.

Among products to be featured in the Clarent stand are the Clarent Gateway, Clarent Command Center and Clarent Connect. Clarent Connect enables the inter-connection of global carrier IP telephony networks. IP telephony clearinghouses play a very important role in the fast- growing IP telephony industry by serving as a one-stop-shop for regional telecommunications service providers who want to meet and exchange voice-over IP calling traffic with other regional providers. To date, more than ten companies have built Clarent-based IP telephony clearinghouses.

Clarent views this year as a period of significant initial implementations of IP telephony networks in Latin America by mainstream and next-generation carriers.

Some countries in Latin America are already deregulated with the majority expected to follow suit during the year 2000. Deregulation of telecommunications in Latin America has helped drive the initial implementations of IP telephony networks. IP Telephony brings efficiency to the new networks and helps enable rapid deployment. Also, bandwidth availability and Clarent's patent-pending Clarent ThroughPacket technology are helping insure quality of service in the IP telephony network. In addition, IP telephony could also decrease the cost of long-distance calls compared to long-distance calls made over the public switched telephone network.

One of Clarent's important Latin America-headquartered customers is Alonet. Alonet is building its own Clarent-based IP telephony network and is also building the world's first Latin American-headquartered global IP telephony clearinghouse based on Clarent products. "We believe the Latin American telecommunications market is ready for IP telephony," said Stifelmann. "Clarent is looking forward to helping additional telecommunications service providers in Latin America build IP telephony networks that could interconnect to the networks of other IP telephony service providers worldwide."

In Latin America, Clarent plans to continue building upon the track record it has established in Asia, Europe and North America, serving over 220 telecommunications service providers, including a number of the world's largest phone companies.

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 interoperability, 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 recent Prospectus, filed with the Securities and Exchange Commission on November 23, 1999.

About Clarent Corporation

Clarent Corporation is a premier provider of scaleable, 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 a Cape Saffron report published in 1999, more minutes travel across Clarent-enabled networks worldwide than those of any other equipment supplier.(a)

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

Clarent is a registered trademark of Clarent Corporation 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.

(a) Cape Saffron "Global IP Voice/ Fax Market 1999". Cape Saffron is an U.K.-based research group focused on the international voice market. http://www.capesaffron.com