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Without GPS, one way to locate a phone could be through trilateration. However, this would require the phone to be connected to 3 (or maybe even 4?) base stations to accurately obtain the phone's location.

In the case that the mobile phone is not connected to a sufficient number of base stations, trilateration would not work. Is there any way that the location could still be obtained from the base station? Would internet access help in any way?

I have often observed how a phone's location can be obtained by tracing a call made to the phone (in several TV shows and movies, which I agree is not a very reasonable or accurate source of information) and by having the call last for a certain duration, during which the location can be obtained. My primary doubt is: what additional information can be obtained in the packets transmitted between the base station and mobile phone, when compared to the case that the phone is idle (not communicating with the base station)? I was wondering if these packets might contain the needed location information.

Assuming that this technique actually works, how would it? How can tracing a call provide location information, unless the phone is connected to a sufficient number of base stations?

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    \$\begingroup\$ You're making the mistake of assuming that there is any truth to the depictions of "phone tracing" used in TV and movies… \$\endgroup\$
    – user39382
    May 17, 2017 at 21:22
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    \$\begingroup\$ All it takes is your phone to be on and transmit one packet identifying the ESN or whatever the phone company uses to track billing. Then they know that you are within x distance of that cell tower. There is also the E911 system that relays your GPS coordinates in the event of an emergency. 1) Don't do things that would make the government want to track you 2) Don't use cellphones if you don't want to be tracked. If the powers that be really wanted to find you, they will eventually \$\endgroup\$
    – Voltage Spike ♦
    May 17, 2017 at 22:05
  • \$\begingroup\$ My iPad generally knows where it is fairly well (maybe 5-10m) and it does not have GPS. This is from the app communicating with Apple servers and I think looking up local Wifi signals, SSIDs and strengths in a database. \$\endgroup\$
    – Spehro Pefhany
    May 17, 2017 at 22:08
  • \$\begingroup\$ Just wanted to add to this discussion that new upcoming base stations for 5G will possibly implement highly directional beams towards mobile stations. Location information can be easily picked up in this case, by a single base station. \$\endgroup\$
    – V-Red
    May 15, 2018 at 1:04

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The base stations always know which cell the phone is closest to. Other than that, the movie version of "tracing" is mostly fictional.

Having an active call causes the phone to transmit a lot more, which might help you find its exact location if you were very close, but does not give you any more location information.

If you are (or are pretending to be) the base station, you can get at the phone's unencrypted IP traffic, which might tell you something. I think the lookups used by Google Play Services for "precise location" (by list of nearest wifi hotspots) is encrypted but it might not be.

A more devious version of location tracking is the Stingray: a portable fake base station. With one of those, you can drive around until you're close to the target phone.

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  • \$\begingroup\$ The base stations do not know. They merely keep track of who's connected at any given point in time. Roaming causes you to switch towers in a non-deterministic manner. At times, a user will be connected to a tower farther away than expected. Radio waves are bouncy. washingtonpost.com/local/… \$\endgroup\$
    – user2497
    May 18, 2017 at 0:34
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With RSSI, the cell tower has idea how close you are. But multipathing and indoors operation (attenuation thru walls) will confuse the RSSI.

With TDMA pulses, the ramp up and ramp down contain lots of cycles at high frequency (2GHz) with 6" wavelengths.

I expect anyone who wants to know has pressured the cellular infrastructure companies to install "location" equipment, just like the Operation System companies have been pressuring into installing certain software modules.

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