Circuit arrangement for determining the zone of origin of a telephone

Abstract

A circuit arrangement determines the identity of a repeater in a telecommunications systems, in particular a telephone system, which, either individually or as one of several of a group, is permanently assigned to a specific zone of origin which is individually characterized by an incoming connection line. During establishment of a telephone connection, in particular an international telephone connection, or a connection foreign to the particular exchange, identification can be made individually in dependence upon the zone of origin of the calling subscriber and a control path, which serves to exchange signals, and which leads to a translator is established. The translator supplies, inter alia, information, for the ongoing connection establishment and for the assignment of a charge pulse train. This is carried out individually by switching elements which can be assigned accordingly, and having been requested, the translator initiates the transmission of a test signal by way of the control path which has been established back to the translator in order to identify the repeater being used. The test signal can be recorded, in assignment to a zone of origin, by an opto-electronic coupler which characterizes the particular zone of origin. A delay element is included between the opto-electronic coupler and a trigger circuit and has a delay time which is matched to the expected duration of interference pulses and the test signal is fed-in for an interval of time which at least exceeds the maximum occurring delay time. A multiple recording is also carried out during this time interval by a display device in order to indicate faults between one or more lines.