[Mashiro]

Well, there are apps like this one for example. The location of the cell towers are from a database hosted by Mozilla. There are also probably community made maps of cell towers where everyone including you and me can mark cell towers. Additionally some providers might also even share their locations of all cell towers including what technologies are supported. My ISP Deutsche Telekom AG does this and I can see cell towers around my area. If I get the code of the cell tower through one of these apps I can even look it up on the ISP map.

Another one:
- https://play.google.com/store/apps/detai...cellmapper