AT&T Co, Cisco Systems Inc and StrataCom Inc have agreed on joint development of Asynchronous Transfer Mode communications technology and services. Financial terms of the agreement were not disclosed. The three said they share a vision of Asynchronous Transfer Mode as the basis of adding high-speed multimedia capabilities to local and wide area networks. The firms will co-operate on definition of standards and development of products and services, beginning with Asynchronous Transfer Mode-to-Frame Relay interworking, they said.