Patent ID: 8718012

Claim:
A mobile communication system which accommodates different types of access networks, comprising: an interwork device having a unit which manages information of correspondence between a base station ID for identifying a base station of an access network of a handover destination and a virtual base station ID for identifying the base station in an access network of a handover source whose ID space is different, and a unit which executes protocol conversion based on said correspondence information, and a mobile terminal having a unit which solves said virtual base station ID from said base station ID and a unit which executes handover between different types of access networks by using said virtual base station ID, wherein the unit which solves a virtual base station ID from said base station ID of said mobile terminal solves said virtual base station ID based on one of: mapping information which correlates said base station ID set in said mobile terminal and a virtual base station ID; a predetermined conversion rule set in said mobile terminal.