Circuit-Switched and Multimedia Subsystem Voice Continuity with Bearer Path Interruption

• US 20130022039A1
• Filed: 09/15/2012
• Published: 01/24/2013
• Est. Priority Date: 05/27/2005
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Mahdi, Kaniz
• Granted Patent: US 10,462,191 B2
• 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 65/1095 Inter-network session transfer or sharing
• CPC Class Codes: H04M 2207/20 hybrid systems
• CPC Class Codes: H04M 3/56 Arrangements for connecting several subscribers to a common circuit, i.e. affording conference facilities video conference systems H04N7/15
• CPC Class Codes: H04M 7/06 using auxiliary connections for control or supervision , e.g. where the auxiliary connection is a signalling system number 7 link
• CPC Class Codes: H04M 7/1205 where the types of switching equipement comprises PSTN/ISDN equipment and switching equipment of networks other than PSTN/ISDN, e.g. Internet Protocol networks
• CPC Class Codes: H04Q 2213/13098 Mobile subscriber
• CPC Class Codes: H04Q 2213/13109 Initializing, personal profile
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13167 Redundant apparatus
• CPC Class Codes: H04Q 2213/13176 Common channel signaling, CCS7
• CPC Class Codes: H04Q 2213/13201 Change-over of service during connection
• CPC Class Codes: H04Q 2213/13248 Multimedia
• CPC Class Codes: H04Q 2213/13389 LAN, internet
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/00226 wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• 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

Abstract

The present invention maintains calls during transfers between different types of subsystems, even when there is a bearer path interruption at the user element due to the original connection from the transferring-out subsystem being dropped before the new connection in the transferring-in subsystem is established. The call signaling leg toward the remote endpoint of the remote party is held, while the call signaling leg toward the user element is moved from the transferring-out subsystem to the transferring-in subsystem and a new bearer path is established via the transferring-in subsystem. During transfers with a bearer path interruption, a portion of the bearer path leading to the remote endpoint may be connected to a media resource function, which will provide an announcement to the remote party. Once the user element is accessible in the transferring-in subsystem, the bearer path is further transferred to the user element via the transferring-in subsystem.

Claims

1. A method comprising:

providing a signaling anchor point in a multimedia subsystem for a first access signaling leg and a remote access signaling leg for a voice call between a user element and a remote endpoint over a bearer path, the first access signaling leg provided for the user element via a transferring-out subsystem;

establishing a second access signaling leg toward a user element via a transferring-in subsystem;

replacing the first access signaling leg with the second access signaling leg, such that the second access signaling leg is anchored at the signaling anchor point; and

providing call signaling via the second access signaling leg and the remote signaling leg to transfer at least a portion of the bearer path connected to the user element from the transferring-out subsystem to the transferring-in subsystem, wherein one of the transferring-in subsystem and the transferring-out subsystem is the multimedia subsystem that supports the voice call over a packet session, and another of the transferring-in subsystem and the transferring out subsystem is a circuit-switched subsystem that supports the voice call over a circuit-switched connection.

2. The method of claim 1 wherein the multimedia subsystem is a third generation wireless packet network and the circuit-switched subsystem is a second generation wireless circuit-switched network.

3. The method of claim 1 wherein there is a perceptible delay between releasing the portion of the bearer path connected to the user element via the transferring-out subsystem and establishing the portion of the bearer path connected to the user element via the transferring-in subsystem.

4. The method of claim 3 further comprising effecting delivery of an audible announcement over a portion of the bearer path connected to the remote endpoint during the perceptible delay.

5. The method of claim 4 wherein effecting delivery of the audible announcement comprises providing call signaling via an intermediate access signaling leg and the remote signaling leg to transfer at least a portion of the bearer path connected to the user element from the transferring-out subsystem to a media resource function, which delivers the audible announcement to the remote endpoint via the bearer path.

6. The method of claim 5 wherein the portion of the bearer path connected to the user element in the transferring-out subsystem is initially transferred to the media resource function for delivery of the audible announcement during the perceptible delay, and is subsequently transferred to the user element via the transferring-in subsystem to reestablish the voice call.

7. The method of claim 1 further comprising receiving a request of the user element to transfer the voice call to the transferring-in subsystem.

8. The method of claim 7 further comprising sending to the user element a message indicating the transfer is being effected via the transferring-out subsystem.

9. The method of claim 8 wherein the user element will release access to the transferring-out subsystem and gain access to the transferring-in subsystem upon receiving the message.

10. The method of claim 7 wherein the user element will automatically release access to the transferring-out subsystem and gain access to the transferring-in subsystem upon sending the request.

11. The method of claim 7 wherein the request is generated from the user element when the user element determines a need to transfer the voice call.

12. The method of claim 7 wherein the request is originated from the user element using at least one of a multimedia subsystem address for a continuity control function, which provides the signaling anchor point, and a directory number within a circuit-switched subsystem, which is associated with the multimedia subsystem address.

13. The method of claim 7 wherein the request is sent via an Unstructured Supplementary Service Data (USSD) channel.

14. The method of claim 1 further comprising effecting subsequent transfers between the transferring-in and transferring-out subsystems.

15. A service node comprising:

a communication interface; and

a control system associated with the communication interface and adapted to;

provide a signaling anchor point in a multimedia subsystem for a first access signaling leg and a remote access signaling leg for a voice call between a user element and a remote endpoint over a bearer path, the first access signaling leg provided for the user element via a transferring-out subsystem;

establish a second access signaling leg toward a user element via a transferring-in subsystem;

replace the first access signaling leg with the second access signaling leg, such that the second access signaling leg is anchored at the signaling anchor point; and

provide call signaling via the second access signaling leg and the remote signaling leg to transfer at least a portion of the bearer path connected to the user element from the transferring-out subsystem to the transferring-in subsystem, wherein one of the transferring-in subsystem and the transferring-out subsystem is the multimedia subsystem that supports the voice call over a packet session, and another of the transferring-in subsystem and the transferring out subsystem is a circuit-switched subsystem that supports the voice call over a circuit-switched connection.

16. The service node of claim 15 wherein the multimedia subsystem is a third generation wireless packet network and the circuit-switched subsystem is a second generation wireless circuit-switched network.

17. The service node of claim 15 wherein there is a perceptible delay between releasing the portion of the bearer path connected to the user element via the transferring-out subsystem and establishing the portion of the bearer path connected to the user element via the transferring-in subsystem.

18. The service node of claim 17 wherein the control system is further adapted to effect delivery of an audible announcement over a portion of the bearer path connected to the remote endpoint during the perceptible delay.

19. The service node of claim 18 wherein to effect delivery of the audible announcement, the control system is further adapted to provide call signaling via an intermediate access signaling leg and the remote signaling leg to transfer at least a portion of the bearer path connected to the user element from the transferring-out subsystem to a media resource function, which delivers the audible announcement to the remote endpoint via the bearer path.

20. The service node of claim 19 wherein the portion of the bearer path connected to the user element in the transferring-out subsystem is initially transferred to the media resource function for delivery of the audible announcement during the perceptible delay, and is subsequently transferred to the user element via the transferring-in subsystem to reestablish the voice call.

21. The service node of claim 15 wherein the control system is further adapted to receive a request of the user element to transfer the voice call to the transferring-in subsystem.

22. The service node of claim 21 wherein the control system is further adapted to send to the user element a message indicating the transfer is being effected via the transferring-out subsystem.

23. The service node of claim 22 wherein the user element will release access to the transferring-out subsystem and gain access to the transferring-in subsystem upon receiving the message.

24. The service node of claim 21 wherein the user element will automatically release access to the transferring-out subsystem and gain access to the transferring-in subsystem upon sending the request.

25. The service node of claim 21 wherein the request is generated from the user element when the user element determines a need to transfer the voice call.

26. The service node of claim 21 wherein the request is originated from the user element using at least one of a multimedia subsystem address for a continuity control function, which provides the signaling anchor point, and a directory number within a circuit-switched subsystem, which is associated with the multimedia subsystem address.

27. The service node of claim 21 wherein the request is sent via an Unstructured Supplementary Service Data (USSD) channel.

28. The service node of claim 15 wherein the control system is further adapted to effect subsequent transfers between the transferring-in and transferring-out subsystems.