WiGLE.net

I was looking at the map to see what gsm/cdma towers I have found. Recently, the only towers I have are t-mobile, while some time ago I had other carriers show on my map. So what happened?

You can get only your own carrier. If you want others you need replace operator sim to catch their network.

Unfortunately yes, there isn't enough information on the "neighboring" cell towers data from the android api to uniquely identify them, so we can only use the tower that you are currently connected to. That said, on the webmaps, if you don't have "only discovered by me" checked, you should be seeing cell towers from many different carriers.

Unfortunately, not every antenna is needs to be registered with the FCC, and the map may not list all the towers in the area. But most are included.

Additionally, many carriers "rent" towers from third-party companies -- and leasing agreements are unknown. If this is the case, the best way to determine carrier coverage is by reading comments in the local area.

hmm I had thought that the 'tower' was added to Wigle based something similar to WiFi points, triangulation on signal strength and phone gps location.

I'm not sure if all towers are listed in the FCC to begin with. I know that a portion are listed with the FAA because they are over 199 feet AGL at which point the special lighting and painting rules go into effect. the ones listed are often shared towers though. Also the building based locations probably don't need to be registered since the antenna isn't separate from the structure.

A thought I had was to query the local planning commission by provider and go the the through building permits. it would be a mess to comb though. Every muni would have a different data structure and you could get back a pile of paper.

From what I've read, lists of cell tower locations are usually kept secret, as some kind of business advantage.

I believe the towers send some metadata including their ICBM address to aid in geolocation services for e911 and smartphone gps assistance. On a BlackBerry, SignalLoc is able to read this out.

This is at least true for Sprint / Boost Mobile towers; YMMV.

I have some data collected from that at http://wrgpmusic.no-ip.org/cheese/towers.kml

Copy that url into the search box in Google Maps and see if you can spot the misconfigured tower that reports a bad location....