| 摘要 |
PURPOSE:To remove the termination of a mishievous call by receiving and discriminating the voice of a calling subscriber by a called subscriber's circuit and generating a call tone from a called subscriber's telephone set only to the termination from a suitable subscriber. CONSTITUTION:A terminating signal from a calling subscriber 14 arrives at a called subscriber's telephone set connecting terminal 9 from an exchange 11 through a telephone line 10. Consequently, a call signal receiving circuit 1 is driven, a circuit 2 for selecting a voice or a pulse signal is driven by an output of the circuit 1 and a DC loop of the telephone line is held to form the call waiting state of the calling subscriber. When a voice or a signal is generated from the calling subscriber, a signal storage circuit 3 collates whether the voice or the signal is the already registered signal or not, and only when the voice or signal is the registered signal, sends its output to a switching circuit 5. The circuit 5 informs the termination to the telephone circuit and the DC calling circuit loop is formed on the basis of a called subscriber's answer. Conse quently, the termination of a mishievous call can be removed.
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