Abstract: A method of sending a multicast message to a plurality of mobile stations in a multicast group is provided. The method involves sending to an access point of a mobile telecommunications network a control message to assign a mobile station to a multicast group. The multicast message is sent to each of one or more access points, each having one or more associated mobile stations in the multicast group. Each access point forwards the multicast message to its associated one or more mobile stations in the multicast group.

Abstract: A mobile telephone system is provided with a new architecture for dealing with voice internet protocol traffic.

Abstract: A real time data transmission method is used in a network in which a real time media gateway is provided to allow access to the internet backbone in addition to the usual GPRS specific gateway. The method involves changing the header in a real time data stream as it passes through the network so that it can pass directly to the real time gateway without passing through the GPRS specific gateway. This ensures that the data stream travels along a more direct route and shortens the headers used in the data stream in the process.

Abstract: A mobile telephone system providing general packet radio service (GPRS) includes a radio network controller (RNC) (2A) and/or a base station controller (BSC) and an associated serving GPRS support node (10A) for each domain. The RNCs (2A) and the SGSNs (10A) are interconnected by an Internet protocol (IP) network. When a mobile telephone (6A) moves from one domain to another, the RNC, in the new domain, takes over handling the mobile telephone. The current SGSN (10A) has a detector (20) which detects whether the existing transmission is a real-time transmission and, if it is, a diverter (22) comes into operation to couple the RNC in the new domain to the current SGSN (10A) rather than its associated SGSN (10A). When the call ends, the current SGSN (10A) hands-over the call to the SGSN (10A) in the new domain. This procedure ensures minimal interruption to real-time services by keeping the call anchored to the current SGSN (10A).

Abstract: A mobile telephone network provides a network operator domain (2a) in which the output from a radio network controller (RAN) (14a) is processed by a voice capable serving GPRS support mode (30) (VC-SGSN).