To reduce the traffic of a control signal by receiving position information from a fixed network and eliminating position registering after the end of a call in a call disconnecting sequence when a call ends.

A mobile station MS transmits a disconnecting signal CC1 to the fixed network NW. The fixed network NW transmits a release signal CC2 to the mobile station MS. The mobile station MS transmits a release completion signal CC3 to the fixed network NW. The fixed network NW transmits a radio channel disconnection signal RC1 to the mobile station MS and position information of the mobile station MS is added to the signal as additional information. Thus, the fixed network NW reports that the mobile station MS is registered in a position register area. When the radio channel disconnecting signal RC1 is received in the mobile station MS, position register information included in its is fetched, a radio channel disconnection recognizing signal RC2 is transmitted to the fixed network NW and the disconnecting sequence is completed.