Internet protocol address preservation in mobile operator networks

A method of operating a mobile communications network by a routing controller arranged to communicate data packets between a terminal and a packet data network via one or more routers, wherein the one or more routers include routing information for routing data packets, the method comprising:

• establishing a data packet pathway for communicating data packets between a first Internet Protocol (IP) address associated with the terminal and a second IP address associated with the packet data network, the data packet pathway including a first local gateway, wherein a local gateway is a point within the mobile communications network through which all data packets communicated over the data packet pathway from the second IP address to the first IP address pass and the first local gateway allocates the first IP address to the terminal from a pool of IP addresses belonging to the first local gateway;
• communicating one or more data packets between the first IP address and the second IP address via the data packet pathway including the first local gateway;
• selecting a second local gateway based on a position of the terminal;
• updating the routing information of at least one of the routers by replacing the first local gateway with the second local gateway in the data packet pathway while maintaining the first IP address allocated by the first local gateway to the terminal;
• and
• communicating one or more data packets between the first IP address and the second IP address via the data packet pathway including the second local gateway.