| 摘要 |
PURPOSE:To eliminate a problem such as repetitive operation of a caller by providing a busy tone detection circuit and a call tone detection circuit to a telephone set main body. CONSTITUTION:If a called party is busy, a busy tone is sent from an exchange from a telephone set circuit 1 and it is detected by a busy tone detection circuit 2. A redial control circuit 3 is started by an output from the busy tone detection circuit 2 and given automatic dialing periodically depending on a redial interval timer set valve set in advance in a redial timer circuit 4. When the called party is not busy and the line is idle and connected to a caller, a called party call tone is detected by a call tone detection circuit 5 to start the buzzer of the buzzer circuit 6 and the calling of the called party is informed to the subscriber via a speaker 7.
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