The Introduction of IFS-1 into a Conventional System: A Preliminary Study

A conventional telephone network and the proposed IFS-1 integrated PCM system [1] differ in their hardware, software, and callrouting policies. IFS-1 has been designed with a measure of hardware and software compatibility with the conventional systems in use in Switzerland: an IFS-1 terminal accepts both analog channels and the full range of existing signalings. However, IFS-1's new network structure may mean costly changes in call routing within the still-conventional part of a mixed-type network as will exist during the introduction period. This paper describes how to put to advantage IFS-1's flexibility so as to avoid any change in the operation of conventional equipment, as well as any subscriber renumbering, due specifically to the introduction of PCM. It further describes a computer program package, developed for a preliminary study of the introduction of PCM into the district network of Berne, Switzerland, and which models the growth of a conventional network and its gradual transition to a fully integrated PCM network.