Who provides cell towers for AT&T network?

Answer 1

ATT and Cingular merged so they share
All the cell companies have an agreement so you could be bouncing off any tower
When there is no agreement you get roaming or delayed charges on a bill.
There a spot in New Mexico when you use your cell phone. It says .... may I have your credit card number. You are roaming out there at like $2.99 a minutes. So it is time to hang up.

Answer 2

There are actually alot of private companies who own the towers. And AT&T and so on lease/rent them. Sometimes multiple carriers are on one tower. For more info about towers try: www.cellreception.com/towers/