Improvements in the circuit of a telephone, particularly in an extra telephone installation with a planned operator controllable positions.

摘要

Data transmission lines for different groups of subscribers are connected through connecting sets to a central control unit. These lines permit exchange of data between the different equipments and the partial controllers for the subscriber circuits, the office sets and the selector memory sets. Other controllers provide control for the exchange telephonic equipment with the connection sets and for the tone generators. A comparator and program controller with memory enables the type of function to be selected from the evaluation of selected signals and special supplementary signals. This permits automatic connection of day or night stations and the selection of another station if these connections cannot be established.