A mobile telecommunications network is proposed with an access network portion having several base station systems that can communicate with a core network portion. The base station systems are adapted to communicate with mobile terminals over a licensed public mobile network air interface and with the core network portion over a predetermined network interface. The network also includes at least one local base station system that is arranged to communicate with the core network portion over the predetermined network interface. This local base station system is further adapted to communicate with mobile terminals over an unlicensed radio interface. The local base station system makes use of an existing fixed network based on IP.