Upon receipt of a location registration request from a mobile terminal, a core network registers the mobile terminal in a node decided according to a subscriber contract of the mobile terminal. Moreover, the core network transmits a temporary subscriber identifier for identification of containing in the node to the mobile terminal. A radio network relays a message signal between a mobile terminal and a core network. When a controller receives a message signal containing the temporary subscriber identifier from the mobile terminal, the controller identifies the node containing the mobile terminal according to the temporary subscriber identifier and transmits the message signal to the node.