T-Mobile has just made a big move to improve its coverage by purchasing a large swath of 700MHz A-Block spectrum from Verizon for nearly $2.4 billion in cash. The UnCarrier -- which has been in a buying mood lately -- said the deal will will help improve its coverage for 158 million people in 21 of the top 30 US markets, including New York, LA, Atlanta and Dallas. It added that the low-band spectrum (which has a greater range than high-band frequencies) will be particularly useful in city suburbs. As part of the deal, it'll also transfer $950 million worth of spectrum to Verizon in several markets, mostly in northern California and Atlanta. Don't get excited about having better 4G coverage just yet, though -- the deal's still subject to approval from the FCC and DoJ, which move at their own speed.