The present invention enables the manufacture of an NTP stratum-1 server using IS-95/2000 synchronous mobile terminals as an external reference clock, instead of an expensive atomic clock or a GPS receiver having a difficulty in indoor reception. It is therefore possible to use an NTP server that provides precise time information by a relatively inexpensive method so as to synchronize a subnet or Internet. By using the NTP servers, precise UTC information and a tick rate stable in the system operation can be provided to the nodes of a network.