reply to Michail
Re: How much... There may be plenty of "spots" in some areas, but the major population centers are very congested. The available spaces on many of these structures is at or below the tree line. And rooftop sites in these areas? Forget about it. All the good sites are taken and extremely difficult to get a workable space. Then you have to lease and zone the site. Even if you co-locate like Lightsquared did with Sprint, you still have space issues, structural issues, and leasing issues. Riding one of the Big 4 is the best way to go. Building from scratch will cost billions more and take a lot longer.