Dual-media messaging using screen telephones on the telephone network

Multimedia communication via the ordinary telephone network can be greatly enhanced by a cooperative evolution of network and terminal capabilities. The authors describe how advances in screen-based telephones, coupled with a signaling protocol that facilitates state-dependent definition of function keys from a remote server, can make relatively complex services easy to use. They describe how coordinated voice and text messaging is facilitated by screen-based telephones and the Analog Display Services Interface (ADSI) protocol. This application illustrates how coordination of the software-driven capabilities of terminals and the public network can enhance user access to network services (connection, messaging, directory, and bridging) and to transactional and other services offered by third-party providers, as well as how it can support end-user applications