I'm confused, how does GPS data get gathered by the telco? Wouldn't that need a backdoor in the OS's GPS software/driver?
As part of this API, is an endpoint that can be made by 911 operators in order to request the position of the phone. It's meant to be part of the E911 services, and is generally linked into the E911 system, but I think can also operate independently.
One of my regrets for the brief period I was working on these systems, is to trigger this API outside of a 911 call, and see if it still works, and whether it would operate without notifying a user. So that's the part I'm missing, I don't know if the API I'm describing can be activated silently from the UE perspective.
As others have pointed out, there are a class of location based services that use non-GPS methods for assisting device location, that may also be at play here, and can be mistaken as GPS by someone who isn't intimately familiar with the technology.
As for a backdoor into the OS, this is totally unnecessary, generally things like GPS and radio's are all wired through the baseband processor, so it's possible for the baseband to process requests without OS involvement. It's a CPU and code for all the network communications, that's runs independent of the rest of the phone, that is doing all the complicated wireless protocols. It depends on the way the standards are written, on what information the OS gets to see from the baseband, and then the way the OS is written on whether that information is actually displayed.
Sorry, I'm also a bit rusty on my telco standards, it's been a few years since I've been working in the telco industry. If you want to dig in and research, I believe LPP (LTE Positioning Protocol) is the spec/standards to dig into.
http://home.bt.com/tech-gadgets/tech-news/google-has-created...
Also, the baseband processor in most phones runs its own code out of the control of the OS and has access to a ton of surprising stuff.
In airplane mode it _shouldn't_ be sending that data.
With aGPS, the cell phones can download up to date GPS almanac from the tower instead of having to lock to GPS satellites to get it.
The parent commenter explicitly write "A-GPS which uses triangulation".
That is simply not true.
Also you asked if carriers need a backdoor, which I answered: "Wouldn't that need a backdoor in the OS's GPS software/driver?"
PS asking a question and berating any answer you don't like is not exactly optimal strategy for getting people to answer your future questions.
The BTS (cell tower) will broadcast the connection info about neighbouring towers and your device will report back the signal strength for each. The network can then make a decision if it needs to move you. This is known as Mobile Assisted Hand Over.
The aim of the game here is maximising signal quality, which is not necessary the same as minimising position to a tower.