PURPOSE: To use a function as a mobile terminal equipment and a function as a usual slave set as required by providing the function as the slave set of the cordless telephone set to the mobile telephone terminal equipment.

CONSTITUTION: Plural mobile base stations 2 are connected to a station 1 and a mobile telephone terminal equipment 20 makes radio communication with a closest mobile base station 2. The mobile telephone terminal equipment 20 has a function as a slave set of the cordless telephone set and a changeover switch 21 is used to select the mode of the telephone set as the mobile telephone terminal equipment or the cordless slave set. When the mobile set enters a subscriber's premises, the changeover switch 21 is thrown to the position of the cordless slave set. Thus, the mobile telephone terminal equipment 20 is used as the cordless slave set, and the terminal equipment 20 is used for a usual telephone set not for a mobile telephone terminal equipment which has a higher charge coefficient.