Structure for electronic trunk line connected communication system - has selectors for local and trunk lines with three and two link lines respectively

摘要

An electronic trunk line connected communication system comprises a central unit, which includes a number of call boxes. Each of these has a logic unit connection to the local line, and another logic unit feeding the trunk line. The latter has two bus-lines connected between it and the trunk line selector. The local line circuit arrangement has three bus-lines between it and the local line selector. Selector components are provided for the code number of the trunk line called and the subscriber number required.