Most companies share towers as well. Say cingular builds a tower in a high traffic area, then alltel comes along and is like "shit we need to fill this hole here", cingular may lease out an antenna on the tower to alltel to make a little side cash. Otherwise we wouldnt be able to walk because towers would be everywhere.

And technically Cingular is ATT now so really its just forming back into the ATT monopoly of the 80's. When you think about it, that could have been a briliant buisness plan. Get the company broken up into several different companies, let them build large networks by themselves, then 20yrs down the road consolidate all the companies back into one company which is probably seeing an absurd amount of new customers and is more powerful than before. But we all know the government wouldnt let that happen......