CHICAGO, Feb. 12 -- Cisco Systems Inc. and Ciena Corp. said they have signed contracts worth millions of dollars to supply equipment for AT&T Corp.'s optical network. Cisco said AT&T has installed Cisco's ONS 15454 Sonet Multiservice Platform optical transport system, a box that allows transport of voice, video and data, as well as the software to manage the system. Exact terms of the deal were not disclosed, but Cisco said it is a multiyear, multimillion-dollar contract. Ciena will supply its CoreDirector switch to AT&T. Ciena signed its first contract with AT&T last May, providing it with its MultiWave Metro fiber optic transport system.