Phones are complex devices that leak our location in countless ways.

3 essential settings for protecting your location data:
Airplane Mode
Location Services
WiFi

We explain how they work & try to demystify location tracking.  https://t.co/0AoMYsZPnB. 

https://t.co/no9dXwUzNT pic.twitter.com/prbGsu7D7M

— Naomi Brockwell (@naomibrockwell) December 14, 2023

 

If we want to be able to use our phones to connect to the Internet or make phone calls wherever we go, we need to subscribe to our cell provider.  They'll either provide us with the physical SIM card to insert into our phone or use the e-SIM that's already built into our device.  SIM stands for Subscriber Identity Module.  It stores your IMSI, or International Mobile Subscriber Identity number, enabling cell Networks to identify your device by authenticating this identity the SIM card ensures that calls and data are correctly routed to and from your phone to maintain network connectivity your phone is constantly scanning for nearby cell towers and connecting to the strongest signal. This means that your cell providers know your location at all times, based on the signals they are receiving from your phone/  If there aren't many cell towers around, this is a rough estimate of your location; with lots of cell towers, the accuracy of location tracking improves.  

"Despite promises to stop us cell carriers are still selling your real time phone location data," Zack Whittaker, Tech Crunch, January 9, 2019. 

It makes sense that cell networks log your location as a byproduct of maintaining connectivity, but did you know that they also have a long history of selling that location data to basically anyone who wants it?  It's pretty egregious.  You might be tempted to think that if you just remove your SIM card, your phone can't connect to cell towers but that's not actually true. Without a SIM, your phone will still connect to cell towers for safety reasons, legal compliance, or certain core services; for example, emergency calls like those to 911.  

"In December [1998], the FCC began requiring Wireless providers to automatically patch through any emergency calls made through their Networks," Chris Dakes, Wired, January 6, 1998.

In many countries, it's mandated that people have access to Emergency Services on their phones regardless of their subscription status with a mobile carrier.  So even without a SIM card, your phone is designed to connect with cell towers to make emergency calls.  Then there's GPS assistance.  Now normally in situations where GPS signals are weak or obstructed, a system on your phone called AGNSS or Assisted Global Navigation Satellite System, will step in to help.  Your phone will either use a SIM or a Wi-Fi connection to download satellite location data to help GPS and other Satellite Systems find your precise location.  However, if your phone doesn't have an active internet connection, it will still connect to cell towers for assistance through a different process known as cellular triangulation or network-based positioning.  This method uses visible cell towers to provide an initial rough estimate of your location.  It can also help speed up the GPS and achieve a more accurate fix, and it works even when your phone doesn't have a SIM in it.  And then there are services like time sync.  Modern smartphones can keep time very accurately on their own but they also can synchronize with a cell Network's time your phone will connect to cell towers to retrieve accurate time data.