Telephone exchange with subscriber terminals identification - distinguishes between call metering and identification pulses sent via same control wire but at different pulse durations

摘要

The telephone exchange has identification pulses differing in their duration w.r.t the call metering pulses sent via the same control wire. Both of the two different pulse signals pass via subscriber-specific connection points in an identification wire connected to one input of a decoder. The potential states of the inputs are interrogated consecutively and cyclically using stored addresses. By comparing the results of this interrogation with the subscriber-specific identification wire, the type of incoming pulse signal can be registered by determining its characteristic duration.