To reserve a communication channel for maintenance for all electronic exchanges which cannot make communication with a maintenance terminal equipment directly or via a LAN on the occurrence of a fault in the LAN.

On the occurrence of a fault in the LAN, upon the reception of a maintenance from a maintenance terminal equipment 7 to an electronic exchange 2, an electronic exchange 4 discriminates it that communication to the electronic exchange 2 cannot be made via a LAN 10, and the maintenance command is transferred to the electronic exchange 2 through an RS232C interface and a speech charge management device 6. The electronic exchange 2 makes processing to the transferred maintenance command and returns the processing result to the electronic exchange 4 via the RS232C interface and the speech charge management device 6. The electronic exchange 4 sends the returned processing result to the maintenance terminal equipment 7 through a MODEM 8 and a data channel 9. Thus, remote maintenance from a remote location to the electronic exchanance 2 disabled with LAN communication is executed by the maintenance terminal equipment 7.