PURPOSE: To easily and accurately perform a time setting when the time setting/ confirmation of the clock circuit of an exchange is performed from a remote maintenance center.

CONSTITUTION: The time information of a reference clock 10 of a centralized maintenance center is digitized at a digital encoding device 9. When the instruction of a time setting is transmitted to a spot exchange side 1 from a maintenance terminal 11 via a packet network 7, a controller 3 receives it, the device calls the centralized maintenance center via an ISDN 6 from a terminal adapter 5 and obtains time information to be a reference. The controller 3 sets the time information in a clock circuit 2. When a confirmation instruction is received from the maintenance terminal 11, the time information of the clock circuit is read and transmitted with the time information via the ISDN 6 to the maintenance terminal 11 via the packet network 7.