Ok first I read the "can N900 be used as a satphone" and now this.
Sorry to point this out but emergency services can't enable your GPS and get your co-ordinats, hell most phones don't even have GPS, particularly in the US where both the networks and the phones are pretty backwards.
This is however mainly because they don't need to cell triangulation is very accurate (tens of metres), certainly in the UK all networks now have this technology and no doubt share it with emergency services and anybody else who can be bothered to ask. Equally they can share it with you, so you know where you are.
However there is another thread on this board somewhere which describes how to remotely access your phone over a data connection and report back GPS co-ordinates, but this relies on you setting the phone up correctly first and reporting its IP address to somewhere when it has a network connection.

No, it isn't. And BTS segmentation is mostly done for reducing the number of phones to service, as each segment is handled as a separate cell. But the whole point is usually moot, see next
It is not even available to then usually, as it depends on Timing Advance which is handled inside the mobile equipment as well as the BTS, but only for the servicing BTS. And there's no means in GSM to remotely force a single phone to do an handover to another BTS. So without the phone actively participating, you usually have the TA for one BTS only, and providers don't even have access to that parameter of a remote BTS. To do a triangulation based upon timing with more than 1 BTS and without support from the ME, you need the non-servicing towers to act as monitors listening to the ME signal sent to the servicing BTS, and comparing this to a global synchronized time raster. This technique isn't implemented in BTS usually. Ergo no triangulation, except when executive forces come with special equipment to do this. (a special case is when the phone just this moment decides to do a handover, then you actually get TA for two BTS (but again afaik the BTS can't be queried about TA for any ME it services), and thus a really good idea where the phone is this moment. All above is for 2G/GSM, for 3G/UMTS WCDMA things might be quite different).
For doing triangulation with ME support see http://lists.openmoko.org/pipermail/...ne/002987.html

3G/WCDMA offers lots of goodies when it comes to variables that the operator can monitor. There are even services offered to let "parents keep track of their teenagers". Or jealous husbands...

I'm still under NDA so I can't share details.

Here in Ireland they "boosted" the sginal to find a missing boy even after the mobile battery had died.
I didn't know this was possible.

Sorry if this upsets anybody

"Officers had worked with the mobile phone company O2 to boost the signal from Robert’s Nokia mobile phone, which went dead shortly after he disappeared. This allowed them to narrow down the search to the area around Inch Strand. An enormous mobile phone mast overlooked the site where Robert’s body was eventually discovered"

http://www.breakingnews.ie/archives/...#ixzz0oGYTL0A6

this is quite likely possible - i have an OLD motorola a1000 and its actually in the manual stating that the emergency services can request gps positions from the device even if agps is turned off (it states it will activate it)

also in a device using agps the gps fix is usually pretty quick in clear sky