PURPOSE: To minimize interference and disturbance due to noise caused by intermodulation and a transmitter and to minimize power consumption by providing a transmission output adjustment means receiving a reception level data and adjusting its own transmission output and a reception sensitivity adjustment means comparing the reception level with a prescribed reference value and adjusting its own reception sensitivity in response to the result of comparison to the telephone set.

CONSTITUTION: Each of a connector 1 and a slave station device 2 is provided with a means 13 sending a reception level data to a transmission destination device, a transmission output adjustment means 12 receiving a reception level data and adjusting its own transmission output and a reception sensitivity adjustment means 16 comparing the reception level with a prescribed reference value and adjusting its own reception sensitivity in response to the comparison result. Then each of the connector 1 and the slave station device 2 sends the reception level data to the transmission destination device to receive the reception level data and to adjust its own transmission output and compares the reception level with a prescribed reference value to adjust its own reception sensitivity in response to the result of comparison. Thus, the interference and disturbance due to noise caused by intermodulation and a transmitter and the power consumption are minimized.