The authors examine the technical evolution that has transformed analog hierarchical rigid voice-oriented wide-area networks into digital flexible intelligent bandwidth-management systems capable of handling voice, data, and image communications. To provide a perspective, the discussion begins with a brief history of wide-area networking evolution. The emerging capabilities of integrated-services digital networks (ISDN) and bandwidth management are then presented, followed by a projection of future capabilities into the 1990s. It is concluded that the available capabilities of ISDN and bandwidth management focus on integration and flexibility, and form the basis for capabilities to be introduced in the 1990s. The authors suggest that whereas voice dominates in 1988 applications in data, image, and video, and the need to integrate them with voice will drive future wide-area capabilities. The emergence of broadband ISDN in the 1990s will provide these capabilities, while forming the infrastructure for the universal information-services network.
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