| 摘要 |
PURPOSE:To awaken the intention of a called party to hook off its handset by receiving a call tone request signal raised through a pushbutton (PB) signal from a telephone set in the talking state to transmit a call tone to the called party whose handset is hooked on. CONSTITUTION:When a subscriber of a telephone set 2 during talking hooks on its handset, a subscriber of a telephone set 19 transmits the call tone transmission request signal 3 by the PB signal to a call tone transmission electronic excange 1. A call tone transmission request signal detecting circuit 4 of the exchange 1 detects the signal 3 and transmits a call tone transmission command signal 5 to a call tone transmission circuit 6, which transmits a call tone 7 to the telephone set 2. The subscriber of the telephone set 2 hooks off the handset so as to transmit a stop request signal 8 of the call tone 7 by the PB signal to a stop signal detection circuit 9, which transmits a stop command signal 10 to the circuit 6 and stops the call tone 7 when the signal 8 is detected. |
