VOICE CONTINUITY AMONG USER TERMINALS

• US 20080160991A1
• Filed: 12/27/2006
• Published: 07/03/2008
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: Ribbon Communications Operating Company, Inc. (Ribbon Communications, Inc.)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Constantinof, Cristian, Sylvain, Dany
• Granted Patent: US 8,600,006 B2
• Time in Patent Office: Days
• US Class Current: 455/426.2
• CPC Class Codes: H04L 65/1093 by adding participants; by removing participants
• CPC Class Codes: H04L 65/1095 Inter-network session transfer or sharing
• 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 4/16 Communication-related supplementary services, e.g. call-transfer or call-hold
• 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 moves service control, including call control, for a user element from any number of subsystems to a multimedia subsystem (MS). Call control for originating or terminating a call in any subsystem as well as transferring the call between user elements is anchored at a continuity control function (CCF) in the MS. A call may be transferred by the CCF from a first user element to a second user element in the same or different subsystems upon receiving a request from the second user element. A user may invoke a transfer from the first user element to the second user element by having the second user element send an appropriate request to the CCF. The request may be provided to the CCF by initiating a call from the second user element that is intended for the CCF, when the call with the first user element is active.

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 call between a first user element and a remote endpoint, the first access signaling leg provided for the first user element;

receiving a request from a second user element to transfer the call from the first user element to the second user element;

establishing a second access signaling leg for the second user element;

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 access signaling leg to transfer at least a portion of a bearer path connected to the first user element to the second user element.

2. The method of claim 1 wherein receiving the request from the second user element comprises receiving a second call initiated from the second user element and intended for a call continuity function of the multimedia subsystem, such that receipt of the second call is indicative of a need to transfer the call to the second user element.

3. The method of claim 2 wherein receipt of the second call while the call is active is indicative of the need to transfer the call to the second user element.

4. The method of claim 3 wherein receipt of the second call when there are no active calls with the first user element and the second user element is indicative of the need to invoke call transfer rules for incoming calls intended for a user who is associated with the first user element and the second user element, and further comprising invoking the call transfer rules in response to receiving the second call when there are no active calls with the first user element and the second user element.

5. The method of claim 2 wherein the second call is routed to the call continuity function via the second access signaling leg.

6. The method of claim 2 wherein the second call is originated from the second user element using at least one of a multimedia subsystem address for the 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.

7. The method of claim 2 wherein the continuity control function resides in a home multimedia subsystem and is invoked as a service by a serving call/session control function for calls from or intended for the first and second user elements.

8. The method of claim 1 wherein the first user element and the second user element are served by a given subsystem.

9. The method of claim 1 wherein the first user element is supported by a transferring-out subsystem and the second user element is supported by a transferring-in subsystem, which is different from the transferring-out subsystem.

10. The method of claim 7 wherein the transferring-out subsystem and the transferring-in subsystem employ different communication techniques.

11. The method of claim 10 wherein one of the transferring-in subsystem and the transferring-out subsystem is the multimedia subsystem and another of the transferring-in subsystem and the transferring out subsystem is a circuit-switched subsystem.

12. The method of claim 11 wherein access to the one of the transferring-in subsystem and the transferring-out subsystem is provided via local wireless access outside of the circuit-switched subsystem.

13. The method of claim 11 wherein the circuit-switched subsystem is provided by a cellular network.

14. The method of claim 1 wherein when the call is originated from the first user element, a continuity control function is invoked as a first service of a plurality of services to be provided in a call signaling path formed by the first access signaling leg and the remote access signaling leg, such that all of the plurality of services other than the continuity control function are provided in the remote access signaling leg, and the remote access signaling leg is anchored at the continuity control function, which provides the signaling anchoring point.

15. The method of claim 1 wherein when the call is terminated at the first user element, a continuity control function is invoked as a last service of a plurality of services to be provided in a call signaling path formed by the first access signaling leg and the remote access signaling leg, such that all of the plurality of services other than the continuity control function are provided in the remote access signaling leg, and the remote access signaling leg is anchored at the continuity control function, which provides the signaling anchoring point.

16. The method of claim 1 further comprising coordinating call signaling exchanges for the call via the second access signaling leg and the remote access signaling leg.

17. A node for providing a continuity control function 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 call between a first user element and a remote endpoint, the first access signaling leg provided for the first user element;

receive a request from a second user element to transfer the call from the first user element to the second user element;

establish a second access signaling leg for the second user element;

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 access signaling leg to transfer at least a portion of a bearer path connected to the first user element to the second user element.

18. The node of claim 17 wherein to receive the request from the second user element, the control system is further adapted to receive a second call initiated from the second user terminal and intended for the call continuity function of the multimedia subsystem, such that receipt of the second call is indicative of a need to transfer the call to the second user element.

19. The node of claim 18 wherein receipt of the second call while the call is active is indicative of the need to transfer the call to the second user element.

20. The node of claim 17 wherein the first user element and the second user element are served by a given subsystem.

21. The node of claim 17 wherein the first user element is supported by a transferring-out subsystem and the second user element is supported by a transferring-in subsystem, which is different from the transferring-out subsystem.

22. The node of claim 21 wherein the transferring-out subsystem and the transferring-in subsystem employ different communication techniques.

23. The node of claim 21 wherein one of the transferring-in subsystem and the transferring-out subsystem is the multimedia subsystem and another of the transferring-in subsystem and the transferring out subsystem is a circuit-switched subsystem.