| 摘要 |
PURPOSE:To discriminate the mischievous calls by securing such a constitution where an answer state is set automatically and immediately after the telephone bell rings once in a call incoming mode and the caller's voices can be heard for a fixed period of time with no pick-up of the telephone handset. CONSTITUTION:When an incoming call is received, a call signal is transmitted from a central office via a trunk. The call signal is supplied through an input terminal 1 and rectified by a rectifying bridge 6 to actuate an A relay 2. Thus a contact a<1> has the make and a B relay 5 is actuated. Then a contact b<1> is closed and a resistance 3 is connected. Thus a loop circuit is formed at the incoming side. As a result, an incoming subscriber answer state is secured even through the handset is not picked up through a subscriber telephone. Thus the caller's voices can be monitored by a speaker 12 via a telephone circuit, the terminal 1 and an IC parts.
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