Communication system including an interworking mobile switching center for call termination

• US 6,996,087 B2
• Filed: 07/31/2001
• Issued: 02/07/2006
• Est. Priority Date: 07/31/2001
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Ejzak, Richard Paul
• Primary Examiner(s): Ngo, Ricky
• Assistant Examiner(s): Juntima, Nittaya
• Application Number:
  US09/919,642
• Publication Number:
  US 20030026245A1
• Time in Patent Office: 1,652 Days
• Field of Search: 370352-356, 370/401, 370/410, 370/467, 370/338, 370/340, 455/435.1, 455/560
• US Class Current: 370/338
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 51/58 Message adaptation for wireless communication
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 69/085 specially adapted for interworking of IP-based networks with other networks
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04W 76/12 Setup of transport tunnels
• 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 88/16 Gateway arrangements
• 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 call terminations.

Claims

1. A method for terminating a call request to a mobile unit being served by an interworking Mobile Switching Center (iMSC) in a communication system comprising a circuit-switched domain, and an Internet Protocol (IP) Multimedia Subsystem (IMS), the method comprising:

sending from the mobile unit to the iMSC a circuit-switched domain registration message;

sending from the iMSC to the IMS a registration indication on behalf of the mobile unit via SIP that identifies the iMSC as the current location at which the mobile unit can be reached;

receiving a call intended for the mobile unit at the IMS;

forwarding by the IMS the call intended for the mobile unit to the iMSC via Session Initiation Protocol (SIP) on an Mx interface, the Mx interface connecting the iMSC to a Call State Control Function (CSCF) in the IMS;

sending by a Serving CSCF (S-CSCF) located in the IMS SIP messages; and

perfomring by the iMSC interworking between SIP call control procedures on the Mx interface and circuit-switched call control procedures towards the mobile unit.

2. A method for terminating a call request in accordance with claim 1, wherein the step of receiving a call intended for the mobile unit at the IMS comprises receiving a call request from a Public Switched Telephone Network (PSTN).

3. A method for terminating a call request in accordance with claim 2, wherein the IMS receives the call request from the PSTN via a Media Gateway Control Function (MGCF), an Interworking Call State Control Function (I-CSCF), and a Serving Call State Control Function (S-CSCF).

4. A method for terminating a call request in accordance with claim 1, wherein the step of receiving a call intended for the mobile unit at the IMS comprises receiving a call request from a second IMS.

5. A method for terminating a call request in accordance with claim 4, wherein the IMS receives the call request from the second IMS via an Interworking Call State Control Function (I-CSCF) and a Serving Call State Control Function (S-CSCF).

6. A method for terminating a call request in accordance with claim 1, wherein the step of receiving a call intended for the mobile unit at the IMS comprises receiving a call request from a Public Land Mobile Network (PLMN).

7. A method for terminating a call request in accordance with claim 6, wherein the IMS receives the call request from the PLMN via a Media Gateway Control Function (MGCF), an Interworking Call State Control Function (T-CSCF), and a Serving Call State Control Function (S-CSCF).

8. A method for terminating a call request in accordance with claim 1, wherein the step of receiving a call intended for the mobile unit at the IMS comprises receiving a call request from a SIP endpoint.

9. A method for terminating a call request in accordance with claim 8, wherein the IMS receives the call request from the SIP endpoint via an IP multimedia network, an Interworking Call State Control Function (I-CSCF), and a Serving Call State Control Function (S-CSCF).

10. A method for terminating a call request in accordance with claim 8, wherein the SIP endpoint is outside of the Public Land Mobile Network (PLMN).

11. A method for terminating a call request in accordance with claim 1, wherein the step of sending by the S-CSCF SIP messages comprises sending the SIP messages directly to the iMSC.

12. A method for terminating a call request in accordance with claim 1, wherein the step of sending by the S-CSCF SIP messages comprises sending the SIP messages to an Interworking Call State Control Function (I-CSCF) in the IMS.

13. A method for terminating a call request in accordance with claim 12, wherein the I-CSCF forwards the SIP messages to the iMSC.

14. A method for terminating a call request in accordance with claim 1, wherein the step of performing interworking between SIP call control procedures comprises mapping call states between SIP and an over-the-air call control protocol.

15. A method for terminating a call request in accordance with claim 1, wherein the step of performing interworking between SIP call control procedures comprises mapping messages between SIP and an over-the-air call control protocol.

16. A method for terminating a call request in accordance with claim 1, wherein the step of performing interworking between SIP call control procedures comprises mapping message parameters between SIP and an over-the-air call control protocol.