Use of SIP messages for location services

1 . A method for a mobile device, comprising:

determining that at least one current network characteristic exceeds a threshold;

including the at least one current network characteristic in a session initiation protocol (SIP) message; and

transmitting the SIP message to a wireless local area network (WLAN).

2 . The method of claim 1 wherein the at least one current network characteristic is included in an attachment of the SIP message.

3 . The method of claim 2 wherein a type of the attachment is specified in one of a plurality of headers of the SIP message.

4 . The method of claim 1 further comprising:

including a service set identifier (SSID) in one of a plurality of header fields of the SIP message.

5 . The method of claim 1 wherein the at least one current network characteristic is included in the SIP message if the mobile device receives service via the WLAN.

6 . The method of claim 1 further comprising:

including information identifying the mobile device in the SIP message, the identifying information comprising at least one of a cell identifier associated with the mobile device and a media access control (MAC) address associated with the mobile device.

7 . The method of claim 1 wherein the at least one current network characteristic pertains to the WLAN.

8 . The method of claim 1 wherein the at least one current network characteristic pertains to a cellular wide area network (WAN).

9 . The method of claim 7 wherein the at least one current network characteristic comprises one or more of a current error rate, a current radio channel, a current signal strength indicator, and one or more access point characteristics.

10 . The method of claim 8 wherein the at least one current network characteristic comprises one or more of a current error rate, a current radio channel, a channel code, a current signal strength indicator, and a list of cell identifiers.

11 . The method of claim 1 further comprising:

periodically collecting a plurality of network characteristics; and

comparing each of the plurality of network characteristics with a corresponding threshold.

12 . The method of claim 1 wherein the SIP message is transmitted to a SIP mobility proxy to assist in a network-controlled decision pertaining to a handoff from the WLAN to a cellular wide area network (WAN).

13 . The method of claim 1 wherein the mobile device is a dual mode mobile device capable of having a simultaneous connection to the WLAN and a cellular wide area network (WAN).

14 . An apparatus for a mobile device, comprising:

a parameter analyzer to determine that at least one current network characteristic exceeds a threshold;

a message composer to include the at least one current network characteristic in a session initiation protocol (SIP) message; and

a message transmitter to transmit the SIP message to a wireless local area network (WLAN).

15 . The apparatus of claim 14 wherein the at least one current network characteristic is included in an attachment of the SIP message.

16 . The apparatus of claim 15 wherein a type of the attachment is specified in one of a plurality of headers of the SIP message.

17 . The apparatus of claim 14 wherein the message composer is further to include a service set identifier (SSID) in one of a plurality of header fields of the SIP message.

18 . The apparatus of claim 14 wherein the message composer is to include information identifying the mobile device in the SIP message, the identifying information comprising at least one of a cell identifier associated with the mobile device and a media access control (MAC) address associated with the mobile device.

19 . The apparatus of claim 14 wherein the at least one current network characteristic pertains to the WLAN.

20 . The apparatus of claim 14 wherein the at least one current network characteristic pertains to a cellular wide area network (WAN).

21 . The apparatus of claim 19 wherein the at least one current network characteristic comprises one or more of a current error rate, a current radio channel, a current signal strength indicator, and one or more access point characteristics.

22 . The apparatus of claim 20 wherein the at least one current network characteristic comprises one or more of a current error rate, a current radio channel, a channel code, a current signal strength indicator, and a list of cell identifiers.

23 . A system comprising:

means for determining that at least one current network characteristic exceeds a threshold;

means for including the at least one current network characteristic in a session initiation protocol (SIP) message; and

means for transmitting the SIP message to a wireless local area network (WLAN).

24 . A computer readable medium comprising executable instructions which when executed on a processing system cause said processing system to perform a method comprising:

determining that at least one current network characteristic exceeds a threshold;

including the at least one current network characteristic in a session initiation protocol (SIP) message; and

transmitting the SIP message to a wireless local area network (WLAN).