PURPOSE: To transfer the fault information by means of an ordinary public circuit by providing a means which inserts and extracts the fault information into and out of a specific channel and a setting microprocessor for transfer circuit of fault information for each type of information transfer circuit.

CONSTITUTION: A microprocessor MP12 connected to a circuit DTI2 is actuated with application of a power supply of a station, and a start signal is transmitted from the processor MP12 via an ordinary public circuit as well as a specific channel of the DTI2. Then the circuit is connected between a local office and a remove maintenance operating station RMC. If a fault is detected at a local office, a control circuit 8 actuates a transmitting circuit 9. This start signal is put into the specific channel by a selector 4 via a CODEC10 and distributed to the specific channel of the circuit DTI2 through a multiplexed separating circuit 6 to be transfered to the RMC.