Hello,

Unlike every cell phone I've owned, the N900 has the ability to control if GPS is turned or or off via user settings. If GPS is turned off then all GPS-requiring applications will not get the GPS feed, which works as expected. Here's the dilemma: I've read that in emergencies (when you dial 911, for example) the provider can get your GPS coordinates (not from cell triangulation, but from the GPS chip). The question is, should a non-technical person need to use the N900 in an emergency, and the GPS setting is turned off, can the emergency service turn on the GPS chipset and get a reading from the N900?

Or does the user GPS on/off functionality override all ability to turn on GPS remotely for emergency purposes?

I'd be alarmed if it were possible to activate the GPS remotely, although it would be a good feature to have in the OS - say you can enter a list of emergency numbers (or maybe hardcode them in if practical), and if you dial any of these numbers via a cell connection the GPS is automatically activated.

Or if there is some signal that can be sent over the cell network to request GPS coordinates, it would be good to have a setting where the user can allow/disallow this. But I sure wouldn't want my phone giving away coordinates willy-nilly.

would be a pretty cool idea for the phone to "phone home" say in the example where your phone is stolen... you could set it that if it does not connect to you home network within say 12hrs that it should send an sms with the gps coords, would be awesome if you knew you were going out to the pub or somewhere you think you could possably get your phone nicked...

Don't know if the phone app has such functionality or not but hardcoding emergency number is not hard at all, considering that the GSM standard mandates that 112 is always directed to nearest emergency response center.

As for GPS coordinates, in many cases cell-triangulation is faster and more accurate.

The "phone home" and other loss-prevention/recovery features are discussed in many threads on this same forum, use the search.

In America it's a legal requirement for GPS chips to be in the phones for many years now, so it's logical to assume the gps is turned on automatically when an emergency call is made by dialling 911

In the UK although 999 is the emergency number, 112 the european number and also 911 all work and get you through to the emergency operator.
I was a network engineer in the UK and had to dial the numbers to test they worked whenever I worked on a cell site.

Unfortunately we can't test this, the 112 operators won't be happy if I call in just to tell them "I'm fine, I'm just testing my phone..."

Is that true? Any sources on that?

I always thought that it is only the GSM triangulation that is used locating emergency phone calls... And adding the fact that GPS don't really work indoors. And how does the phone call then enter the phones GPS chip system and relay the information?

Err, pretty sure there's no legal requirement for GPS chips to be in phone in the USA. Might be confusing that with triangulation using network towers.

In the 3G network there are several methods for determining the handset location, UE (handset) based GPS, UE with AGPS network assisted, then CellID+RTT, CellID dependant on the accuracy requested by the SMLC. If all 3G positioning methods are not fulfilled then the handset will switch to 2G and use 2G positioning methods.

I beleive that 911 will override any settings in the phone and switch on the GPS, but even if it doesn't have a GPS signal the network can still find the handset location using other methods.

Positioning can also be requested using a mobile terminated location request, this is completely invisible to the end user. I believe use of this feature would require a warrent of some kind.

GSM triangulation alone is very accurate, no need for GPS for emergencies, especially given the fact that if you report an emergency using your cell phone, then you can always be located. With GPS you don't have that comfort, as you can be e.g. in a tunnel, not to mention time to get a GPS fix (triangulation is instant).

I'm not sure if emergency services are able to get your location anyway, even if they can, I'm not sure if it's deployed in every country with GSM networks, can anyone confirm/deny?