In places where GPS isn’t available, in an underground transit station for example, it really seems like a no brainer to just use the cell towers in range to triangulate your location.
The police can already track the location of your phone using cell towers. That’s how 911 knows where you are when you call them (AFAIK). Why isn’t it just available for the phone itself to figure out its own location so you can use it to navigate?
Your phone uses tons of shit to figure out where it is. Cell towers, known WiFi access points, GPS, GLONASS, some others I forget the name of.
One time we moved a state away and brought our router without changing the SSID. For like 2 weeks our phones would show us back at the old place whenever we were on the wifi