TELEPHONE DEVICE

摘要

PURPOSE:To transmit two information on a conduction mode and a service interruption mode by holding a call state or switching automatically this call state according to an active or inactive state of a telephone talking circuit in a switching mode between the conduction and service interruption states. CONSTITUTION:A pair of power supply cables 71 are used as communication lines in a service interruption mode. At the same time, automatic changeover switches 14-1 and 14-2 are provide into a telephone 200. When a conduction state is changed to a service interruption state, a calling route is held and then changed to a service interruption calling route by an automatic service interruption switching circuit 60 owing to an on-hook mode. No current flows to the circuit 60 in a conduction state lasting from a call mode of the calling route in a service interruption mode. Thus a call state is held and a normal call mode is reset by an on-hook state. Therefore no manual operation is needed when a call is through.