| 摘要 |
PURPOSE:To decrease the congestion of a telephone network by generating an alarm sound at a prescribed time after a redial key is depressed at a period other than a time from the closing of a line to a dial calling so as to apply automatic redialing. CONSTITUTION:An off-hook detection output is inputted to a control section 11 from a loop detection circuit 3. When no dial pulse is sent after off-hook, a telephone line 1 is connected to a monitor circuit 8 via line change-over switches 2, 5 and a dial tone is monitored. The control section 11 checks the states of the circuit 3 and a polarity inversion detection circuit 10 and when the state represents a closed loop and polarity non-inverting state, the control section 11 starts an alarm ringing circuit 15 to ring the alarm and connects the line 1 to an automatic dial section 6.
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