Most companies have some spectrum holdings they're not using.

I think in AT&T's case the reason that they're not using some of their spectrum is because they don't have complete national coverage in any of the unused bands.

Spectrum auctions don't come up that often so the big telcos usually purchase some whenever they have an auction. They then try to buy or trade spectrum to fill in any missing pieces.

If AT&T built out LTE using their unused spectrum some would be in 1700, some would be in 700 and there would be some parts of the country where the would not be able to deploy LTE at all.

http://www.phonescoop.com/articles/article.php?a=187 ... »

http://www.phonescoop.com/articles/article.php?a=99& ... »

I think the plan is to deploy LTE in 700 and try to buy or trade for any missing licenses. That may still be what happens, but if the t-mobile merger goes through they would have rich 1700 holdings, national coverage and double or triple the megahertz or a normal license in many parts of the country. Similar to what Verizon has in 700 for their LTE deployment, although still not quite as good because it's at a higher frequency.