Key TakeawaysT-Mobile announced an agreement Tuesday to acquire most of U.S. Cellular's wireless operations for about $4.4 billion.The deal would give T-Mobile a larger footprint among more rural areas of the U.S.U.S. Cellular shares jumped soon after the opening bell. Telecommunications giant T-Mobile (TMUS) announced Tuesday that it would acquire "substantially all" of U.S. Cellular's (USM) wireless operations in a deal valued at $4.4 billion. U.S. Cellular customers would receive access to T-Mobile's exp ...