A mobile communications system includes a system controller and cell sites having base station systems. The network between the system controller and the base station systems is a packet-switched network, such as an Internet Protocol (IP) network. In one embodiment, the mobile communications system is a General Packet Radio Service (GPRS) system. The system controller is a serving GPRS support node (SGSN), and the network between the SGSN and the base station systems includes a Gb network. In one arrangement, IP addressing is used to communicate messages between the base station systems and the SGSN.