CIENA Selected by Telefonos de Mexico - TELMEX - As a Strategic Vendor for Next-generation Network; Awards Contract to CIENA for LightWorks Architecture Deployment.

Business Editors/High-Tech Writers

CIENA(R) Corporation (NASDAQ:CIEN), a leading provider of intelligent optical networking systems and software, today announced that it has been selected by Telefonos de Mexico (TELMEX) (NYSE:TMX), as the supplier of intelligent optical networking solutions for its next-generation network. TELMEX, Mexico's largest telecommunications service provider, will use CIENA's solution in its network operations.

The two companies have signed an agreement that encompasses CIENA's LightWorks(TM) suite of products. CIENA already has begun shipping products and deployment is underway in TELMEX's more than 70,000-kilometer fiber optic digital network. Initially, TELMEX is deploying CIENA's optical switching products to build Latin America's premier next-generation network to accommodate continued growth in data service traffic.

"The selection of CIENA as a key strategic next-generation networking vendor is the result of an exhaustive process designed to determine which solution could help us continue to provide innovative services and programs to our customers," said Eduardo Gomez Chibli, director of technical and long distance for TELMEX.

"CIENA's LightWorks architecture was the clear winner. The benefits derived from products that have distributed intelligence were the key factors in the decision to develop this relationship with CIENA," concluded Chibli.

TELMEX is widely considered one of the world's strongest carriers, having recently been ranked at the top of Forbes.com's list of "The World's Best Telecom Companies." In that feature, TELMEX was chosen as the "Spotlight" company for its ability to adapt its technology to the market it serves. It is TELMEX's ability to provide a wide range of services and programs for Mexico's business and residential markets that has distinguished the carrier from its peers around the globe.

"One of CIENA's ongoing corporate objectives is to continue building our base of top-tier carrier customers around the world. Given TELMEX's reputation for the highest performance standards, we are excited about our relationship with this dynamic and innovative service provider," said Arely Castellon, vice president and general manager, Latin America for CIENA. "TELMEX is known for its ability to identify the needs of the markets it serves and create products accordingly, so we are looking forward to working with TELMEX as a key strategic vendor and to building a next-generation network that creates value for TELMEX and its customers."

In addition to the service-enabling characteristics of LightWorks, the CIENA architecture is expected to help TELMEX identify potential failures before they happen, reduce the amount of steps required to set up circuits and simulate network growth for future expansion planning.

About TELMEX

TELMEX (NYSE:TMX) is the leading telecommunications company in Mexico with more than 13.6 million telephone lines in service, 1.7 million lines equivalents for data transmission and 986,000 accounts with access to the Internet. TELMEX offers telecommunications services through a more than 70,000 kilometer fiber optic digital network. TELMEX and its subsidiaries offer a wide range of advanced telecommunications, data and video services, Internet access as well as integrated telecom solutions for corporate customers. Please visit www.telmex.com.

ABOUT CIENA

Serving some of the most innovative service providers across Europe, Asia and the Americas, CIENA Corporation (NASDAQ: CIEN) develops intelligent optical networking systems and software for integrated communications networks. CIENA's LightWorks(TM) network architecture enables a new generation of highly customized optical services and dramatically improves the fundamental economics of service-provider networks. By simplifying the network and reducing the cost to operate it, CIENA is helping carriers realize the economic and competitive advantages associated with managing a simpler, smarter network. Additional information about CIENA can be found at www.ciena.com.

NOTE TO INVESTORS

This press release contains certain forward-looking statements based on current expectations, forecasts and assumptions of CIENA (the Company) that involve risks and uncertainties. Forward-looking statements in this release, including, but not limited to, the cost savings, deployment timing and network management benefits of the Company's products, are based on information available to the Company as of the date hereof. The Company's actual results could differ materially from those stated or implied in such forward-looking statements, due to risks and uncertainties associated with the Company's business, which include the risk factors disclosed in the Company's Report on Form 10-Q filed with the Securities and Exchange Commission on May 23, 2002. Forward-looking statements include statements regarding the Company's expectations, beliefs, intentions or strategies regarding the future and can be identified by forward-looking words such as "anticipate," "believe," "could," "estimate," "expect," "intend," "may," "should," "will," and "would" or similar words. The Company assumes no obligation to update the information included in this press release, whether as a result of new information, future events or otherwise.