Abstract: The invention relates to a registration method used for registering at least one dual mode mobile station (MMS) with an associated private base station (DBS). The private base station is connected to the public telephone network (PSTN, ISDN) and uses, for transmission and reception, frequencies which are close to or identical to those used in a cellular radio system. The dual mode mobile station can operate either in “cordless” mode, used to communicate via said private base station, or in “cellular” mode, used to communicate via base stations (BTS) within the cellular radio system. Registration of the dual mode mobile station with the private base station constitutes a preliminary stage enabling the operation of the dual mode mobile station in “cordless” mode, whereby, following each incoming or outgoing call, a conversation can be established between the dual mode mobile station and other telephone equipment, via the private base station.