Telephone communication system control unit - regulates connection process of communication channels using coded data signals

摘要

A central control for a telephone communication system has a coupling network between exchanges that uses transmitted digital data for generating the various control signals. In particular the interaction between various line conditions, i.e. dialling condition signals, line occupied signals etc. are controlled. A number of subscriber stations are coupled over a coupling network with control being provided by a central unit operating over a data transmission line handling PCM data. A second control unit operates in the case of disturbances affecting the main unit.