Radiotelecommunications system having a mobile terminal that operates both in cellular mode and in cordless mode

Claim 1

A radiotelecommunications system having a mobile terminal equipped with a subscriber identity module and designed to operate in a first mode referred to as "cellular mode" in a cellular network having a plurality of cells, the radiotelecommunications system comprising: a private base station independent from said cellular network and connected by wire to a wired telecommunications network, said private base station occupying at least a part of one of the cells of the cellular network, to which cell the cellular network has allocated at least one frequency from among all of the frequencies available in the cellular network using a predetermined frequency re-use scheme; wherein the mobile terminal comprises: a selector enabling the mobile terminal to operate in a second mode referred to as "cordless mode" when the mobile terminal is situated within a predetermined zone in the vicinity of the private base station, in which mode the mobile terminal can set up a call to or receive a call from said wired telecommunications network by communicating by radio with said private base station, radio communication taking place on at least one frequency selected from a predetermined set of one or more frequencies also chosen from among all of the frequencies available in the cellular network except at least those frequencies which are allocated to said cell, said selector comprising: storage means for storing said predetermined set of one or more frequencies in a storage zone of the two-part unit formed by the mobile terminal and by the subscriber identity module, wherein, when the mobile terminal operates in cellular mode, said predetermined set of one or more frequencies is previously transmitted by radio from a base station of the cellular network that is closest to the mobile terminal, so that said predetermined set of one or more frequencies can be stored in said storage means.