| 摘要 |
PURPOSE:To enable to select and control only the call of the desirable caller, by restoring the automatic response circuit automatically after delivering the busy tone to the caller for a given time, if the discrimination of reception of exclusive code is not made within a given time for the telephone set at the incoming side. CONSTITUTION:The telephone unit 2 at incoming side automatically responses 4 to the call out signal from the subscriber, and the caller delivers the exclusive code immediately after the caller knows the response at the incoming side. Further, when the telephone unit 2 discriminates 5 the exclusive code for reception, the incoming of telephone is informed with the speaker 8. In this case, the telephone set 2 at incoming side delivers busy tone to the caller when the discrimination of exclusive code reception is not made within a given time, and the telephone line can automatically cut off by restoring the automatic response circuit 4 after performing the delivery of busy tone for a given time. Thus, the call for desirable caller only is selected and the incoming call signal is made, controlling the incoming telephone set. |
