RRLP Support if GPS is Disabled?

[mail_e36]

RRLP stands for Radio Resource LCS (Location) Protocol. Apparently this is implemented in some modern smartphones in order to provide your GPS coordinates to your mobile operator in an emergency (http://en.wikipedia.org/wiki/RRLP). I have read that the N900 supports RRLP. The apperent problem with RRLP is that the operator does not have to authenticate to get your GPS information. This is based on a white paper (http://openbsc.gnumonks.org/trac/attachment/wiki/HAR2009/har2009-gsm-report.pdf) from a conference called Hacking At Random 2009 ("Report on the OpenBSC powered GSM network at HAR2009").

The N900 has the ability to turn GPS on and off via the Maemo GUI. The question becomes, would an unauthenticated RRLP request provide your N900's GPS coordinates if GPS is disabled via the GUI?

This posting sprung from another similar posting which many people seemed to have misinterpreted (http://talk.maemo.org/showthread.php?t=47680)

[tomaszrybak]

The only way to be sure if n900 turns on GPS when requested by cell operator would be to take BTS, compile and install OpenBSC (http://openbsc.gnumonks.org/trac/), connect n900 to this ad-hoc network and request RRLP response from mobile. This however requires hardware access and running GSM network, which might require permission, depending on the country.

I have quickly looked at source of OpenBSC and while it contains some RRLP functionality it seems to be in separate module - I am not sure how well it is integrated into full suite. I have not looked at it carefully and might have missed something.

On the other hand I have skimmed through GSM specification 3GPP TS 04.31 describing RRLP and other location services. Positioning Instruction message send to MS (phone) by cell network contains mandatory field Positioning Method. One of possible values of this field is 1 - GPS. I am not sure but from wording of this document it looks like phone must obey this request - but word used for field is "which location method should be used". So it is still not sure what mobile will do with disabled GPS when such a request will come.

[mail_e36]

Thanks for your response, I guess this will continue to be an open question on the N900.