Method and system using a media gateway for handoff of a multi-mode mobile station

• US 9,215,641 B1
• Filed: 05/19/2011
• Issued: 12/15/2015
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Delker, Jason R., Everson, John M.
• Primary Examiner(s): Sams, Matthew
• Application Number:
  US13/111,140
• Time in Patent Office: 1,671 Days
• Field of Search: 455436-444, 4555521-5531, 370331-334
• US Class Current: 1/1
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04W 36/0022 for transferring data sessions between adjacent core network technologies
• CPC Class Codes: H04W 36/02 Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A multi-mode mobile station includes a first interface for wireless communication with a wireless local area network (WLAN) and a second interface for wireless communication with a wireless wide area network (WWAN). A call control system routes all calls to and from the multi-mode mobile station through a media gateway that serves as an anchor point for handoffs between the WLAN and WWAN. For example, while involved in a call that has a WLAN call leg from the media gateway, the multi-mode mobile transmits a handoff request. The call control system then establishes a WWAN call leg from the media gateway, and the multi-mode mobile station stores in a buffer any media received via the WWAN call leg. The call control system subsequently transmits a handoff instruction to the multi-mode mobile station. In response, the multi-mode mobile station plays out the stored media and drops the WLAN call leg.

Claims

1. A method for call handoff between a first wireless network and a second wireless network for a multi-mode mobile station, said multi-mode mobile station including a first interface for wireless communication with said first wireless network and a second interface for wireless communication with said second wireless network, said method comprising:

said multi-mode mobile station becoming engaged in a call with an endpoint via said first interface;

while said multi-mode mobile station is engaged in said call with said endpoint via said first interface, said multi-mode mobile station transmitting a handoff request, wherein said handoff request comprises a Session Initiation Protocol (SIP) UPDATE message that requests an update to involve said second interface in said call;

after transmitting said handoff request, said multi-mode mobile station becoming engaged in said call with said endpoint via said second interface and receiving media for said call via said second interface;

said multi-mode mobile station storing said media, thereby accumulating stored media;

said multi-mode mobile station receiving a handoff instruction, wherein said handoff instruction comprises a SIP response message that directly responds to said SIP UPDATE message; and

in response to said handoff instruction, said multi-mode mobile station conveying said stored media and continuing said call with said endpoint via said second interface.

2. The method of claim 1, wherein said multi-mode mobile station becoming engaged in a call with said endpoint via said first interface comprises said multi-mode mobile station becoming engaged in said call via a first call leg, wherein said first call leg extends between an anchor point and said multi-mode mobile station via said first wireless network.

3. The method of claim 2, wherein said multi-mode mobile station becoming engaged in said call with said endpoint via said second interface comprises said multi-mode mobile station becoming engaged in said call via a second call leg, wherein said second call leg extends between said anchor point and said multi-mode mobile station via said second wireless network.

4. The method of claim 3, further comprising:

in response to said handoff instruction, said multi-mode mobile station dropping said first call leg.

5. The method of claim 1, wherein said first wireless network is a wireless local area network (WLAN) and said second wireless network is a wireless wide area network (WWAN).

6. The method of claim 1, wherein said call is a voice call.

7. The method of claim 1, further comprising:

while said multi-mode mobile station is engaged in said call with said endpoint via said first interface, said multi-mode station determining that said second wireless network is available and preferred.

8. The method of claim 7, wherein said handoff request requests a handoff of said call from said first wireless network to said second wireless network.

9. The method of claim 1, wherein said multi-mode mobile station becoming engaged in said call with said endpoint via said second interface comprises:

said multi-mode mobile station registering with said second wireless network;

said multi-mode mobile station receiving an incoming call request via said second interface; and

said multi-mode mobile station automatically answering said incoming call request.

10. The method of claim 9, wherein said incoming call request includes a caller identification that identifies said multi-mode mobile station.

11. The method of claim 1, wherein said multi-mode mobile station conveying said stored media comprises said multi-mode mobile station playing said stored media through a speaker.

15. The method of claim 1, wherein said SIP response message includes a numeric status code and a textual phrase.

12. A multi-mode mobile station, comprising:

a first wireless interface for communication with a first wireless network;

a second wireless interface for communication with a second wireless network; and

a buffer, wherein said multi-mode mobile station is configured to store in said buffer media received during a handoff of a call from said first wireless network to said second wireless network and to convey said stored media in response to receiving a Session Initial Protocol (SIP) response message that directly responds to a SIP UPDATE message transmitted by said multi-mode mobile station, wherein said SIP UPDATE message requests an update to involve said second wireless interface in said call.

13. The multi-mode mobile station of claim 12, wherein said SIP response message includes a numeric status code and a textual phrase.

14. The multi-mode mobile station of claim 12, wherein said first wireless network is a wireless local area network (WLAN) and said second wireless network is a wireless wide area network (WWAN).