TRIPARTITE COMMUNICATION EQUIPMENT OF PUBLIC TELEPHONE SET

摘要

PURPOSE:To realize a tripartite call from a public telephone set by generating a tripple channel for tripartite call in a tripartite speaking circuit, and compulsorily interrupting the call line of the public telephone set when the absence of a call rate is detected. CONSTITUTION:A control part 2 generates the triple channel for tripartite call in the tripartite speaking circuit 3 so as to attain the tripartite call, and transmits two metering pulses toward a public telephone set A from a metering pulse reproducing and transmitting circuit 6 by shifting two metering pulses arriving by routes lest they are overlapped when they are overlapped hourly if a metering pulse detection circuit 5 detects the metering pulses arriving by routes. The compulsory disconnection circuit 8 supervises the presence or absence of the possibility of the reception of the call rate in the public telephone set A. When it detects the absence, it compulsorily disconnects the call line of the public telephone set A. Thus, the tripartite call is attained from the public telephone set.