Verizon COO Lowell McAdam has said at the Fortune Brainstorm Tech conference that he expects US regulators will approve AT&T's proposed $39 billion acquisition of T-Mobile. AT&T was facing a wireless airwaves crunch and grabbing the fourth-largest wireless carrier was a logical way to get it, he argued. Verizon has been visibly less vocal in its opposition to the proposed merger than Sprint Nextel, the third largest US provider.