at&t of Morristown, NJ, has chosen nec America of Herndon, VA, to supply Synchronous Optical Network (Sonet) transport equipment. Under a five-year agreement, at&t will purchase nec America`s Intelligent Transport System-2400A Sonet Add/Drop Multiplexer. After test and evaluation, at&t is expected to deploy the equipment as part of the company`s ongoing upgrade of its 40,000 mi fiber-optic network to Sonet technology. The multiplexing equipment is based on nec`s Synchronous Digital Hierarchy 4-fiber bidirectional line-switched OC-48 (2.5-Gbit/sec) ring technology.