Ciena Selected for BT's 21st Century Network.

LINTHICUM, Md. -- Ciena(R) Corporation (NASDAQ:CIEN), the network specialist, today announced that BT has selected Ciena as a preferred supplier to support its 21st Century Network (21CN), a five-year project to transform BT's business and enable the cost-effective delivery of next-generation converged, multimedia communications across a single multiservice network. BT has announced it expects to conclude contractual agreements with named preferred suppliers over the summer. BT plans to deploy Ciena's technology as it migrates services from the existing UK public switched telephone network (PSTN) to a single, multiservice internet protocol (IP)-based network.

Under the multi-year agreement, BT plans to deploy Ciena's optical switching and transmission and Ethernet transport platforms to enable network convergence and accelerate service delivery. Designed to reduce network complexity and the costs associated with service fulfillment, Ciena's platforms will help enable a network architecture for BT designed with significantly fewer network elements.

"The 21CN project exemplifies BT's commitment to innovation and its dedication to going above and beyond for the benefit of its customers," said Gary Smith, president and CEO, Ciena. "Ciena's applications-driven technology is ideally suited for innovative networks like 21CN. We are proud to continue working with an industry leader like BT as it embarks on this massive transformation."

Smith continued, "We believe BT selected Ciena for its technology leadership, demonstrated performance in building large, adaptive carrier-class networks, and commitment to delivering vendor-interoperable solutions, while enabling the convergence of an IP network via an optical backbone. Ciena's platforms also provide BT an unsurpassed level of network flexibility to enable a practical, seamless migration from TDM to IP."

BT's 21CN, a global IP infrastructure that carries voice, data and Internet services on a single network, aims to enable BT customers to access any communications service from any device, anywhere at broadband speed. The 21CN will deliver more choice, control and accessibility, as well as increased flexibility, reliability and security for BT's business and residential customers.

Today's announcement from BT on the 21CN preferred suppliers is available at www.bt.com/newscentre. BT enquiries to BT Group Newsroom 24-hour number: 020 7356 5369. From outside the UK dial + 44 20 7356 5369.

ABOUT CIENA

Ciena Corporation is the network specialist, focused on expanding the possibilities for its customers' networks while reducing their cost of ownership. The company's systems, software and services target and cure specific network pain points so that telcos, cable operators, governments and enterprises can best exploit the new applications that are driving their businesses forward. For more information, visit www.ciena.com.

NOTE TO INVESTORS

This press release contains certain forward-looking statements based on current expectations, forecasts and assumptions that involve risks and uncertainties. These statements are based on information available to the Company as of the date hereof; and Ciena's actual results could differ materially from those stated or implied, due to risks and uncertainties associated with its business, which include the risk factors disclosed in its Report on Form 10-Q, which Ciena filed with the Securities and Exchange Commission on March 3, 2005. Forward-looking statements include statements regarding Ciena'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. Ciena assumes no obligation to update the information included in this press release, whether as a result of new information, future events or otherwise.