3 ms·

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?

nitrogen 8y ago
Cell networks triangulate a pretty accurate device location in order to connect you to the best cell towers for where you are. 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.
- mehrdadn 8y ago
  GPS != cell networks, and I'm asking what is actually happening, not for a hypothetical guess (which I can make too).
  - packetized 8y ago
    https://en.m.wikipedia.org/wiki/Enhanced_GPS https://en.m.wikipedia.org/wiki/Enhanced_GPS
  - ShorsHammer 8y ago
    The article mentions it's aGPS which uses tower triangulation. But this would be requiring a data link back to the network provider I'd assume. In airplane mode it _shouldn't_ be sending that data. https://en.m.wikipedia.org/wiki/Assisted_GPS https://en.m.wikipedia.org/wiki/Assisted_GPS
    - TomVDB 8y ago
      aGPS has nothing to do with cell tower triangulation. 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.
      - nitrogen 8y ago
        Read the wikipedia page before downvoting the parent commenter, who was correct: "A-GPS augments that by using cell tower data to enhance quality and precision when in poor satellite signal conditions."
        TomVDB 8y ago
        Feel free to point out where the Wikipedia says that it helps with triangulation. (Hint: it does not.) The parent commenter explicitly write "A-GPS which uses triangulation". That is simply not true.
  - nitrogen 8y ago
    Not a hypothetical guess. Carriers have access to location data from multiple sources and have been selling it. Some of those sources are combined with GPS in this particular case. 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.
- kingosticks 8y ago
  They obviously can calculate position, but it's not required for GSM handover. 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.
nerdbaggy 8y ago
Cell networks can just ask the device for it. It’s used for legitimate purposes then the not so legitimate purposes
kevin_nisbet 8y ago
I'm greatly simplifying here, but basically there is an API between the telco network and the chipset on the UE (User Equipment). This API is primarily a control interface for general telco signalling, roaming between towers, receiving an SMS, etc. 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.
- mehrdadn 8y ago
  Thank you!!
BurningFrog 8y ago
There is a mandated function for it in all phones that's intended for locating people making 911 calls.
timthorn 8y ago
In the UK, the Telco responsible for emergency call handling worked with Google to get a mechanism built in to Android that sends a SMS of your location as soon as you dial the emergency number. http://home.bt.com/tech-gadgets/tech-news/google-has-created-a-new-location-tool-to-help-emergency-services-find-you-faster-11364075879276 http://home.bt.com/tech-gadgets/tech-news/google-has-created...

nitrogen 8y ago

Cell networks triangulate a pretty accurate device location in order to connect you to the best cell towers for where you are. 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.

mehrdadn 8y ago
GPS != cell networks, and I'm asking what is actually happening, not for a hypothetical guess (which I can make too).
- packetized 8y ago
  https://en.m.wikipedia.org/wiki/Enhanced_GPS https://en.m.wikipedia.org/wiki/Enhanced_GPS
- ShorsHammer 8y ago
  The article mentions it's aGPS which uses tower triangulation. But this would be requiring a data link back to the network provider I'd assume. In airplane mode it _shouldn't_ be sending that data. https://en.m.wikipedia.org/wiki/Assisted_GPS https://en.m.wikipedia.org/wiki/Assisted_GPS
  - TomVDB 8y ago
    aGPS has nothing to do with cell tower triangulation. 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.
    - nitrogen 8y ago
      Read the wikipedia page before downvoting the parent commenter, who was correct: "A-GPS augments that by using cell tower data to enhance quality and precision when in poor satellite signal conditions."
      - TomVDB 8y ago
        Feel free to point out where the Wikipedia says that it helps with triangulation. (Hint: it does not.) The parent commenter explicitly write "A-GPS which uses triangulation". That is simply not true.
- nitrogen 8y ago
  Not a hypothetical guess. Carriers have access to location data from multiple sources and have been selling it. Some of those sources are combined with GPS in this particular case. 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.
kingosticks 8y ago
They obviously can calculate position, but it's not required for GSM handover. 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.

nerdbaggy 8y ago

Cell networks can just ask the device for it. It’s used for legitimate purposes then the not so legitimate purposes

kevin_nisbet 8y ago

I'm greatly simplifying here, but basically there is an API between the telco network and the chipset on the UE (User Equipment). This API is primarily a control interface for general telco signalling, roaming between towers, receiving an SMS, etc. 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.

mehrdadn 8y ago
Thank you!!

BurningFrog 8y ago

There is a mandated function for it in all phones that's intended for locating people making 911 calls.

timthorn 8y ago

In the UK, the Telco responsible for emergency call handling worked with Google to get a mechanism built in to Android that sends a SMS of your location as soon as you dial the emergency number. http://home.bt.com/tech-gadgets/tech-news/google-has-created-a-new-location-tool-to-help-emergency-services-find-you-faster-11364075879276 http://home.bt.com/tech-gadgets/tech-news/google-has-created...