Communication system for providing roaming between an internet protocol multimedia system and a circuit-switched domain

• US 6,871,070 B2
• Filed: 07/31/2001
• Issued: 03/22/2005
• Est. Priority Date: 07/31/2001
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ejzak, Richard Paul
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): RAMPURIA, SHARAD K
• Application Number:
  US09/919,641
• Publication Number:
  US 20030027569A1
• Time in Patent Office: 1,330 Days
• Field of Search: 455/435.1, 455/432.1, 455/445, 455/426.1, 370/328, 370/338, 370/401, 370/352, 370/356
• US Class Current: 455/435.1
• CPC Class Codes: H04L 51/58 Message adaptation for wireless communication
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1043 Gateway controllers, e.g. media gateway control protocol [MGCP] controllers
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04W 60/04 using triggered events
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: H04W 80/10 adapted for application session management, e.g. SIP [Session Initiation Protocol] connection management H04W76/00; arrangements for session management H04L67/14
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

A communication system includes User Equipment (111), Radio Access Network (RAN) (121), a packet-switched domain (131), an IP Multimedia Subsystem (IMS) (141), a circuit-switched domain (151), a Domain Name System (DNS) (165), a Charging Gateway Function (CGF) (134), an EIR (135), a Transport Signaling Gateway (T-SGW) (146), and a Roaming Signaling Gateway (R-SGW) (147). The CS domain (151) includes an interworking Mobile Switching Center (iMSC) (201). The iMSC (201) translates the CS domain registration, call control, feature control, and feature invocation procedures associated with the access technology to standard SIP procedures. The media gateway (MGW) (173) under the control of the iMSC (201) converts the air interface media flow into a packet stream that is managed by SIP procedures within the IMS (141). The iMSC (201) thereby allows for interworking between circuit-switched and packet-switched domains for provision of features and services while roaming between different kinds of home and serving systems.

Claims

1. A method for registering a mobile unit with a communication system including a serving system and a home system, the serving system comprising an interworking MSC (iMSC) and an Internet Protocol Multimedia Subsystem (IMS), the home system comprising a Gateway MSC (GMSC) and a Home Subscriber Server (HSS), the method comprising:

performing a location update procedure by the mobile unit;

processing by the serving system the registration by authenticating the mobile unit and informing the HSS of the location of the current serving system;

determining that the serving system must process the mobile unit as an iMSC; and

emulating the services of the iMSC by the IMS.

2. A method for registering a mobile unit in accordance with claim 1, wherein the step of performing a location update procedure is done to indicate a change in the serving system.

3. A method for registering a mobile unit in accordance with claim 1, further comprising the step of originating a call with the serving system.

4. A method for registering a mobile unit in accordance with claim 3, wherein the step of originating a call with the serving system comprises:

receiving a call request at the serving system;

performing interworking between call control procedures between the iMSC and IMS;

forwarding the call to a Border Gateway Control Function (BGCF) and Media Gateway Control Function (MGCF); and

interworking between the MGCF and a Public Switched Telephone Network (PSTN).

5. A method for registering a mobile unit in accordance with claim 1, further comprising the step of performing features and services for the mobile unit within the IMS in the serving system.

6. A method for registering a mobile unit in accordance with claim 1, further comprising the steps of:

receiving a call termination by the GMSC in the home system;

forwarding the call termination to the IMS in the serving system; and

forwarding the call termination to the iMSC in the serving system.

7. A method for registering a mobile unit in accordance with claim 6, wherein the step of forwarding the call termination to the IMS comprises:

forwarding the call termination from the GMSC to the MGCF;

forwarding the call termination from the MGCF to the I-CSCF; and

forwarding the call termination from the I-CSCF to the S-CSCF.

8. A method for registering a mobile unit with a communication system including a serving system and a home system, the serving system comprising a mobile switching center (MSC) and an interworking MSC (iMSC), the home system comprising an Internet Protocol Multimedia Subsystem (IMS) and a Home Subscriber Server (HSS), the method comprising:

performing a location update procedure by the mobile unit;

processing by the serving system the registration by authenticating the mobile unit and informing the HSS of the location of the current serving system; and

determining if the serving system can process the mobile unit as an iMSC.

9. A method for registering a mobile unit in accordance with claim 8, wherein the step of performing a location update procedure is done to indicate a change in the serving system.

10. A method for registering a mobile unit in accordance with claim 8, further comprising the step of originating a call with the serving system.

11. A method for registering a mobile unit in accordance with claim 10, wherein the step of originating a call with the serving system comprises:

receiving a call request at the serving system;

performing interworking between call control procedures by the iMSC in the serving system and the IMS in the home system; and

forwarding the call from the IMS to the called party.

12. A method for registering a mobile unit in accordance with claim 8, further comprising the step of performing features and services for the mobile unit within the IMS in the home system.

13. A method for registering a mobile unit in accordance with claim 8, further comprising the steps of:

receiving a call termination by the IMS in the home system; and

forwarding the call termination to the iMSC in the serving system.