| 摘要 |
PURPOSE:To realize high-speed data transmission and voice service with one telephone circuit and to permit data communication even during the voice service if a monitoring and control item changes in state, by providing additionally a circuit for switching the circuit to a remote monitoring controller and a telephone set. CONSTITUTION:When the handset of the telephone device 5 is lifted for telephone service from a transmitting and receiving station 1 to a transmitting and receiving station 2, its off-hook signal is sent to a state change detecting circuit 13 as a telephone call signal to the transmitting and receiving station 2 and then sent to a telephone device 6, and then the buzzer sounds to call the telephone of the transmitting and receiving station 2. Once the handset of the called transmitting and receiving station 2 is lifted, the sounding of the buzzer of the telephone device 6 is stopped by the off-hook signal and a circuit connection relay contact 42 is connected to the telephone device 6; and data showing that the transmitting and receiving station 2 is in a voice servicable state is sent to the transmitting and receiving station 1 and the circuit switching relay contact 41 of the transmitting and receiving station 2 is connected to the telephone device 6. When the necessity of data transmission rises during the voice service, a circuit switching relay contact 31 or 41 is connected preferentially to a modulator 17 or 18 only while the data is transmitted, thus performing the data transmission. Consequently, the high-speed data transmission and voice service are permitted with only one telephone circuit and the data transmission is carried out preferentially even during the voice service. |
