SYSTEM AND METHOD FOR HANDOFF OF SESSION FROM VOIP INTERFACE TO CELLULAR INTERFACE OF DUAL-MODE DEVICE

• US 20090023450A1
• Filed: 02/28/2008
• Published: 01/22/2009
• Est. Priority Date: 07/16/2007
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: George, Richard, Shatsky, Alexander
• Granted Patent: US 8,725,148 B2
• Time in Patent Office: Days
• US Class Current: 455/442
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1053 IP private branch exchange [PBX] functionality entities or arrangements circuit switched PBXs H04M3/00
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04M 2203/1091 Fixed mobile conversion
• CPC Class Codes: H04M 3/42314 in private branch exchanges
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 7/1235 where one of the core networks is a wireless network
• CPC Class Codes: H04W 36/00224 between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]
• CPC Class Codes: H04W 36/0033 with transfer of context information
• 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

A method and system for handing off an active VoIP call with a remote party from a VoIP interface of a dual-mode device to a cellular interface of the dual-mode device. A cellular call is established between a PBX IP/PSTN gateway and the cellular interface. Media relating to the first termination point of the VoIP leg of the active call is then redirected to the cellular call and the VoIP leg is terminated.

Claims

1. A method of handing off an active call between a Voice-over-IP (VoIP) interface and a cellular interface of a dual-mode device, wherein the active call is with a remote party, wherein the dual-mode device includes the VoIP interface for wireless communications over an IP network and the cellular interface for wireless communications over a public land mobile network (PLMN), and wherein the IP network includes a communications server, the active call including a VoIP leg from the dual-mode device to a first termination point, the method comprising the steps of:

receiving, at the communications server, a handoff instruction message from the VoIP interface of the dual-mode device;

initiating a cellular call from the communications server to the cellular interface of the dual-mode device via the PLMN;

sending a ringing message from the communications server to the VoIP interface of the dual-mode device;

receiving an accepted message via the PLMN with regard to the cellular call confirming connection of the cellular call with the cellular interface of the dual-mode device;

sending a message to the first termination point with regard to the active call containing instructions to connect to the cellular call; and

terminating the VoIP leg.

2. The method claimed in claim 1, wherein the active call is established in a first dialog, and wherein the step of sending the message to the first termination point comprises sending a SIP re-INVITE message to the first termination point in association with the first dialog, the SIP re-INVITE message containing Session Description Protocol (SDP) information for the cellular call.

3. The method claimed in claim 2, wherein the first termination point comprises a PBX having a PTSN gateway, the active call includes a PSTN leg terminated at the PBX, the cellular call is terminated at the PBX, and wherein the re-INVITE message causes the PBX to connect the PSTN leg to the cellular call.

4. The method claimed in claim 2, wherein the first termination point comprises a VoIP-capable device within the IP network, the communications server includes a PBX having an interface to the PLMN, the cellular call is terminated at the PBX, and wherein the re-INVITE message causes the VoIP-capable device to redirect media from the first dialog to the PBX in a new media path, and the PBX connects the new media path to the cellular call.

5. The method claimed in claim 1, wherein the communications server comprises a call control server and a PBX, the PBX having an IP interface to the IP network and a PSTN interface, and wherein the step of receiving a handoff instruction message comprises receiving the handoff instruction message from the dual-mode device at the call control server, and sending a SIP INVITE message from the call control server to the PBX addressed to the cellular interface of the dual-mode device.

6. The method claimed in claim 5, wherein the SIP INVITE message contains no SDP offer.

7. The method claimed in claim 6, wherein said handoff instruction message comprises a custom SIP message containing a handoff feature indicator and containing a cellular interface number for the dual-mode device and a call identifier regarding the active call.

8. The method claimed in claim 7, including a step of receiving a SIP 180 RINGING message at the call control server from the PBX, and wherein the step of sending a ringing message to the dual-mode device comprises sending a 200 OK message in response to the custom SIP message.

9. The method claimed in claim 6, wherein the PBX receives the accepted message confirming connection of the cellular call, and wherein the method includes a step of sending a SIP 200 offer from the PBX to the call control server in response to the SIP INVITE message, wherein the SIP 200 offer contains SDP information for the cellular call.

10. The method claimed in claim 9, wherein the VoIP leg is established in a first dialog, and wherein the step of sending the message to the first termination point comprises sending a SIP re-INVITE message to the first termination point from the call control server in association with the first dialog, the SIP re-INVITE message containing the SDP information for the cellular call.

11. The method claimed in claim 10, wherein the active call includes a PSTN leg terminated at the PBX and the first termination point comprises the PBX, and wherein the re-INVITE message causes the PBX to connect the PSTN leg to the cellular call.

12. The method claimed in claim 10, wherein the first termination point comprises a VoIP-capable device within the IP network, and wherein the SIP re-INVITE message is sent to the VoIP-capable device via the PBX in accordance with the first dialog, and wherein the SIP re-INVITE message causes the VoIP-capable device to redirect media associated with the first dialog to the PBX in a new media path as specified by the SDP information, and the PBX connects the new media path to the cellular call.

13. The method claimed in claim 10, further including a step of sending a first SIP ACK message from the call control server to the first termination point to complete the re-invite process, and sending a second SIP ACK message from the call control server to the PBX in response to the SIP 200 offer, wherein the second SIP ACK message contains SDP information for the first termination point in connection the first dialog, thereby causing the PBX to route media from the cellular call to the remote party.

14. The method claimed in claim 7, wherein the custom SIP message comprises a custom SIP INVITE message.

15. The method claimed in claim 7, wherein the custom SIP message comprises a custom SIP SUBSCRIBE message.

16. A communications server for managing a handoff of an active call between a Voice-over-IP (VoIP) interface and a cellular interface of a dual-mode device, wherein the active call is with a remote party, wherein the dual-mode device includes the VoIP interface for wireless communications over an IP network and the cellular interface for wireless communications over a public land mobile network (PLMN), the active call including a VoIP leg from the dual-mode device to a first termination point, the communications server comprising:

a call processing module configured to receive a handoff instruction message from the VoIP interface of the dual-mode device; and

a PSTN interface configured to initiate a cellular call from the communications server to the cellular interface of the dual-mode device via the PLMN,

wherein the call processing module is configured to send a ringing message to the VoIP interface of the dual-mode device, the PSTN interface is configured to receive an accepted message via the PLMN with regard to the cellular call confirming connection of the cellular call with the cellular interface of the dual-mode device, and the call processing module is further configured to send a message to the first termination point with regard to the active call containing instructions to connect to the cellular call and to terminate the VoIP leg.

17. The communications server claimed in claim 16, wherein the active call is established in a first dialog, and wherein the call processing module is configured to send a message to the first termination point by sending a SIP re-INVITE message to the first termination point in association with the first dialog, the SIP re-INVITE message containing Session Description Protocol (SDP) information for the cellular call.

18. The communications server claimed in claim 17, wherein communication server comprises a PBX containing the PSTN interface and a call control server containing the call processing module, the PBX and call control server being connected by the IP network, and wherein the first termination point comprises the PBX, the active call includes a PSTN leg terminated at the PBX, the cellular call is terminated at the PBX, and wherein the PBX is configured to connect the PSTN leg to the cellular call based on the re-INVITE message.

19. The communications server claimed in claim 17, wherein the first termination point comprises a VoIP-capable device within the IP network, the communications server includes a PBX containing the PSTN interface and a call control server containing the call processing module, the PBX and call control server being connected by the IP network, and wherein the cellular call is terminated at the PBX, and wherein the VoIP-capable device is configured to redirect media from the first dialog to the PBX in a new media path based on the re-INVITE message, and the PBX is configured to connect the new media path to the cellular call.

20. The communications server claimed in claim 16, wherein the communications server includes a PBX containing the PSTN interface and a call control server containing the call processing module, the PBX and call control server being connected by the IP network, and wherein the call processing module in the call control server is configured to send a SIP INVITE message from the call control server to the PBX addressed to the cellular interface of the dual-mode device based on the handoff instruction message, and wherein the PBX is configured to initiate the cellular call in response to the SIP INVITE message.

21. The communications server claimed in claim 20, wherein the SIP INVITE message contains no SDP offer.

22. The communications server claimed in claim 21, wherein said handoff instruction message comprises a custom SIP message containing a handoff feature indicator and containing a cellular interface number for the dual-mode device and a call identifier regarding the active call.

23. The communications server claimed in claim 22, wherein the PBX is configured to send a SIP 180 ringing message to the call control server in response to receipt of ringing confirmation from the PSTN regarding the cellular call, and wherein the call control server is configured to send a ringing message by sending a 200 OK message in response to the custom SIP message.

24. The communications server claimed in claim 21, wherein the PBX is configured to receive an accepted message confirming connection of the cellular call, and, consequent thereon, to send a SIP 200 offer to the call control server in response to the SIP INVITE message, wherein the SIP 200 offer contains SDP information for the cellular call.

25. The communications server claimed in claim 24, wherein the VoIP leg is established in a first dialog, and wherein the call processing module is configured to send a message to the first termination point by sending a SIP re-INVITE message to the first termination point in association with the first dialog, the SIP re-INVITE message containing Session Description Protocol (SDP) information for the cellular call.

26. The communications server claimed in claim 25, wherein the active call includes a PSTN leg terminated at the PBX and the first termination point comprises the PBX, the cellular call is terminated at the PBX, and wherein the PBX is configured to connect the PSTN leg to the cellular call based on the re-INVITE message.

27. The communications server claimed in claim 25, wherein the first termination point comprises a VoIP-capable device within the IP network, the cellular call is terminated at the PBX, and wherein the call control module is configured to send the SIP re-INVITE message to the PBX and the PBX is configured to relay the SIP re-INVITE message to the VoIP-capable device in accordance with the first dialog, and the VoIP-capable device is configured to redirect media associated with the first dialog to the PBX in a new media path as specified by the SDP information based on the SIP re-INVITE message, and the PBX is configured to connect the new media path to the cellular call.

28. The communications server claimed in claim 25, wherein the call control server is configured to send a first SIP ACK message to the first termination point to complete the re-invite process, and to send a second SIP ACK message to the PBX in response to the SIP 200 offer, wherein the second SIP ACK message contains SDP information for the first termination point in connection the first dialog, thereby causing the PBX to route media from the cellular call to the remote party.

29. The communications server claimed in claim 22, wherein the custom SIP message comprises a custom SIP INVITE message.

30. The communications server claimed in claim 22, wherein the custom SIP message comprises a custom SIP SUBSCRIBE message.

31. A computer program product comprising a machine-readable medium having encoded thereon computer-executable instructions for handing off an active call between a dual-mode device and a remote device, wherein the dual-mode device includes a Voice-over-IP (VoIP) interface for wireless communications over an IP network and a cellular interface for wireless communications over a public land mobile network (PLMN), and wherein the IP network includes a communications server, the active call including a VoIP leg from the dual-mode device to a first termination point, the computer-executable instructions comprising:

instructions for receiving, at the communications server, a handoff instruction message from the VoIP interface of the dual-mode device;

instructions for initiating a cellular call from the communications server to the cellular interface of the dual-mode device via the PLMN;

instructions for sending a ringing message from the communications server to the VoIP interface of the dual-mode device;

instructions for receiving an accepted message via the PLMN with regard to the cellular call confirming connection of the cellular call with the cellular interface of the dual-mode device;

instructions for sending a message to the first termination point with regard to the active call containing instructions to connect to the cellular call; and

instructions for terminating the VoIP leg.