Standards for UPT introduction and evolution

UPT (universal personal telecommunication) was conceived as a universal service which would allow users to enjoy mobility across many types of networks whilst still retaining the convenience of familiar calling and billing conditions. Standardisation of network signalling solutions in CCITT Study Group XI is helping to bring this dream towards reality. The author describes the probable course of this standardisation and shows that introduction of UPT features must be in stages because of network limitations. A view is offered as to the likely evolution of UPT service features in new networks and the progressive introduction of control by users