Mobile Phones Give Away Your Location
For another article illustrating this principle, with a great graphic, check out this piece.
A mobile phone network needs to know where a specific phone is located; only then can it connect it to the right towers and send and receive signals from it. You should assume that, whenever your phone is powered on, your mobile provider knows where it’s located. Your phone’s location can be pinpointed with greater precision in areas with more cell towers (for example, busy cities).
At the same time, there are plenty of apps which can similarly record your location by asking your phone (rather than cell network) for it. Such location tracking, while it could be terrifyingly useful to someone who is tracking you, is fortunately also a bit easier to turn off (here is how you can disable it on Android and iOS). In general, a good rule is to only give apps location permission if they absolutely need it. A taxi app might require location to know where to pick you up; location access might make a weather app more convenient but you can still manually type in names of cities.
If you’re planning to meet with a sensitive contact and worry that a government or telecom might be using location data to figure out that you’re both in the same place, do not just turn off your phones right before the meeting or once you arrive at the meeting location. If both people’s devices suddenly disappear off the network, anyone who’s tracking them might easily notice. It’s much smarter to try to instead simulate normal activity, for example by leaving your phones turned on at home or in the office prior to meeting (or turning it off hours beforehand, if you're the type of person whose phone battery regularly dies). That way, anyone who’s trying to track you through your mobile phone alone will assume you’re at one of your usual locations, rather than at a confidential meeting. (Don’t forget that there are many other ways in which governments could possibly still track you, for example through CCTV cameras or credit card transactions.)
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The two pieces below describe a politician from the German Green Party, who asked his mobile network for his location data. He then worked with a group of journalists who recreated all his travels across Germany, based on cell tower location data alone:
Locating a German politician by cell tower data alone (The article is sadly only available in German. This article is just slightly outdated in one way – it’s much easier now to make calls and send messages through encrypted channels like Signal and WhatsApp, and telecoms providers and governments cannot easily access the contents of such calls or messages)
For a more in depth look on the security implications of app location data, check out the guide we designed here at Internews