| 摘要 |
PURPOSE:To know reply of a phoning object even when a monitoring circuit is stopped or volume is lowered by providing a ringing tone detecting circuit and a calling indicating tone generating circuit that generates indicating tone during calling. CONSTITUTION:A telephone circuit 1 is connected to an automatic dialing section 6 by changing a change-over switch 5 to upper side and dial transmission is performed. After completion, the switch 5 is changed again to lower side and the circuit 1 is connected to a monitoring circuit 7. Consequently, audible sound modulated by 16Hz received from the circuit 1 is generated from the circuit 7. At the same time, the audible sound is detected by a ringing tone detecting circuit 8 and a calling indicating tone generating circuit 9 is started to generate calling indicating tone from the circuit 9. When a phoning object makes a reply, ringing tone is stopped, and calling indicating tone generated from the circuit 9 is stopped. Accordingly, even when volume of the circuit 7 is lowered, a caller can know reply of the other party by stoppage of calling indicating tone, and can reply without letting those around him hear the voice of the other party. |
