Roaming between circuit-switched and all-IP networks

• US 20060092925A1
• Filed: 10/26/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Svensson, Sven Anders Borje, Renschler, Martin, So, Raymond
• Application Number:
  US11/259,406
• Publication Number:
  US 20060092925A1
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/104 in the network
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04L 65/1095 Inter-network session transfer or sharing
• CPC Class Codes: H04W 8/06 Registration at serving network Location Register, VLR or user mobility 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 88/16 Gateway arrangements

Abstract

A temporary address assignment server in an IP network assigns a temporary number to use for setting up a mobile terminated call to a mobile station roaming in an IP network. The temporary number is supplied to a switching node, such as a Mobile Switching Center, in a circuit switched network. The Mobile Switching Center sets up a connection with a Media Gateway by sending a call setup message to a Media Gateway Control Function. The call setup message includes the temporary number assigned by the temporary address assignment server. The Media Gateway Control Function uses the temporary number to establish a media session with the mobile station.

Claims

1. A method of call delivery to a roaming mobile station to enable interworking between a circuit-switched home network and an IP network, said method comprising:

receiving an origination request at a mobile switching center in said home network of the mobile station;

sending a location request from said mobile switching center to a home location

register in the home network responsive to said origination request sending a temporary number request from said home location register to a temporary address assignment server in said IP network, said temporary number request including a signaling address for said mobile station in said IP network;

allocating a temporary number to said mobile station and associating said temporary number with said signaling address for said mobile station;

returning said temporary number to said home location register responsive to said temporary number request;

forwarding said temporary number from said home location register to said mobile switching center;

sending a call set-up message including said temporary number from said mobile switching center to a media gateway control function in said IP network to set-up a circuit connection between said mobile switching center and a media gateway;

establishing a media connection between said media gateway and said home network;

sending an call invitation from said media gateway control function to said temporary number received from said mobile switching center; and

redirecting said call invitation to the mobile station.

2. The method of claim 1 wherein redirecting said call invitation comprises:

forwarding said call invitation to said temporary address assignment server;

mapping said temporary number to said signaling address for said mobile station stored by said temporary address server;

sending a redirection response including said signaling address from said temporary address server to said media gateway; and

sending a second call invitation from said media gateway to said signaling address of said mobile station to initiate a media session with said mobile station.

3. A communication network comprising:

a mobile switching center including a call processing circuit operative to;

receive an origination request for a mobile terminated call to a mobile station roaming in an IP network;

send a location request to a home location register responsive to said origination request;

receive a location request response including a temporary number assigned to said mobile station from said home location register;

send an initial address message including a said temporary number to a media gateway;

a home subscriber server operative to;

receive said location request from said mobile switching center;

send a temporary number request to a temporary address server, said temporary number request including a signaling address for said mobile station in said IP network;

receive a temporary number assignment from said temporary address assignment server;

send a location request response to said mobile switching center including said assigned temporary number;

a temporary address assignment server operative to;

receive said temporary number request from said home location register;

assign a temporary number to said mobile station responsive to said temporary number request;

store said temporary number and said signaling address in a temporary directory;

receive a call set-up message including said previously assigned temporary number;

redirect said call- set-up message to said mobile station signaling address;

a media gateway control function including a call processing circuit operative to;

receive a call set-up message from said mobile switching center including said temporary number; and

establish a media session with said mobile station using said temporary number responsive to said call set-up message.

4. The communication network of claim 3 wherein the media gateway control function establishes a media session with said mobile station by sending a first invitation to the temporary number, receiving a redirection message including the signaling address of the mobile station responsive to the first invitation, and sending a second invitation to the signaling address contained in the redirection message.

5. The communication network of claim 4 wherein said temporary number serves is further operative to receive said first invitation from said media gateway control function, and to redirect said invitation by sending a redirection response to said media gateway control function.

6. A method of facilitating a call to a mobile station roaming in an IP network, said method comprising:

assigning a temporary number to a mobile station;

associating the temporary number with a signaling address of said mobile station and storing said association in memory;

receiving a call invitation including said temporary number from a media gateway control function; and

redirecting said invitation to said signaling address of said mobile station to initiate a media session with said mobile station.

7. The method of claim 6 wherein said invitation comprises a SIP INVITE request.

8. The method of claim 7 wherein redirecting said invitation comprises sending a SIP redirection response to said media gateway control function, said redirection response including a signaling address for said mobile station.

9. The method of claim 8 further comprising establishing a media session said mobile station.

10. The method of claim 9 wherein establishing a media session with said mobile station comprises sending a call invitation to said signaling address of said mobile station.

11. A temporary address assignment server to enable interworking between a circuit-swtiched network and an IP network, said temporary address assignment server comprising:

a server for allocating temporary numbers to mobile stations roaming in said IP network, and storing said temporary numbers along with corresponding signaling addresses of said mobile stations in a database;

a SIP server to receive call invitations for said mobile stations, said call invitations including a previously assigned temporary number, and to redirect said call invitations to the signaling address associated with said temporary number in said database.

12. The temporary address assignment server of claim 11 wherein said call invitation comprise a SIP INVITE request.

13. The temporary address assignment server of claim 12 wherein said signaling processor redirects said call invitation by sending a SIP redirection response to the originator of the call invitation.

14. A method of facilitating a call to a mobile station roaming in an IP network, said method comprising:

receiving a location request from a switching node in a circuit-swtiched network, said request including a signaling address in said IP network;

obtaining a temporary number from a temporary address assignment server;

forwarding a signaling address in said IP network for said mobile station to said temporary address assignment server;

forwarding said temporary number received from said temporary address assignment server to said switching node.

15. The method of claim 14 wherein obtaining a temporary number from a temporary address assignment server comprises sending a temporary number request to said temporary address assignment server responsive to said location request if said mobile station is roaming in said IP network.

16. A home subscriber server to enable interworking between a circuit-swtiched network and an IP network, said home subscriber server comprising:

a subscriber database for storing subscriber information, including location information and signaling addresses;

a server operatively connected to said subscriber database, said server operative to;

obtain a temporary number from a temporary address assignment server;

forward a signaling address for said mobile station to said temporary address assignment server; and

forward said temporary number received from said temporary address assignment server to said switching node.

17. The home subscriber server of claim 16 wherein the server obtains said temporary number by sending a temporary number request to said temporary address assignment server responsive to a location request from a switching node.