The Department of Justice puts a lot of faith in T-Mobile's ability to increase its position in the enterprise and government segment when they have historically been unable to and discount the ability of new entrants when they have been historically been successful. In the last year, two companies (LightSquared and Dish) have decided this is a market they want to enter because they think they can compete in it--betting billions of dollars against what the DOJ thinks and what MetroPCS, Leap Wireless, and Clearwire have shown to be able to do. None of the three companies have an easy time, but that's the hallmark of a competitive market.