Communication system

A service control device used for an IMS (IP Multimedia Subsystem) network, said IMS network comprising:

• a femtocell base station;
• said service control device;
• and
• a core device that controls a call,
• wherein said service control device has an SGSN (Serving GPRS Support Node) function section that sends back a signal transmitted from a network that uses a communication procedure different from that of the IMS network in the same manner as a signal transmitted from an SGSN,
• wherein a plurality of service control devices are provided in said IMS network and one of the plurality of service control devices has been designated as a representative service control device,
• wherein said representative service control device correlatively stores identification information of each of said plurality of service control devices and address information of service control devices identified with the identification information, and
• wherein said representative service control device has representative control means that receives a P-TMSI (Packet-Temporary Mobile Subscriber Identity) contained in a PDP (Packet Data Protocol) context succession request signal from a UE (User Equipment) according to a handover communication procedure prescribed in the applicable standard after the UE moves, identifies a service control device identified with the identification information as a service control device that manages a femtocell base station to which the UE belonged before it moved unless the service control device identified with the identification information contained in the received P-TMSI is its own representative service control device, and forwards said PDP context succession request signal to the identified service control device.

A femtocell base station used for an IMS (IP Multimedia Subsystem) network, said IMS network comprising:

• said femtocell base station;
• a service control device;
• and
• a core device that controls a call,
• wherein said service control device has an SGSN (Serving GPRS Support Node) function section that sends back a signal transmitted from a network that uses a communication procedure different from that of the IMS network in the same manner as a signal transmitted from an SGSN, a plurality of service control devices being provided in said IMS network, one of the plurality of service control devices having been designated as a representative service control device, and
• wherein said femtocell base station has transmission means that transmits a P-TMSI (Packet-Temporary Mobile Subscriber Identity) that accords with a communication procedure prescribed in an applicable standard and that contains identification information of a service control device that manages its own femtocell base station to a UE (User Equipment) that belongs to the femtocell base station.

A communication method for a communication system that configures an IMS (IP Multimedia Subsystem) network,

• wherein said IMS network comprises:
• a femtocell base station;
• a service control device;
• and
• a core device that controls a call,
• wherein said service control device has an SGSN (Serving GPRS Support Node) function section that sends back a signal transmitted from a network that uses a communication procedure different from that of the IMS network in the same manner as a signal transmitted from an SGSN, a plurality of service control devices being provided in said IMS network,
• wherein one of the plurality of service control devices has been designated as a representative service control device,
• wherein said representative service control device correlatively stores identification information of each of said plurality of service control devices and address information of service control devices identified with the identification information,
• wherein the communication method comprises:
• a transmission step that causes said femtocell base station to transmit a P-TMSI (Packet-Temporary Mobile Subscriber Identity) that accords with a communication procedure prescribed in an applicable standard and that contains identification information of a service control device that manages its own femtocell base station to a UE (User Equipment) that belongs to the femtocell base station, and
• a representative control step that causes said representative service control device to receive the P-TMSI contained in a PDP (Packet Data Protocol) context succession request signal from the UE according to a handover communication procedure prescribed in the applicable standard after the UE moves, identify a service control device identified with the identification information as a service control device that manages a femtocell base station to which the UE belonged before it moved unless the service control device identified with the identification information contained in the received P-TMSI is its own representative service control device, and forward said PDP context succession request signal to the identified service control device.