Verizon and AT&T celebrated the postponed turn-up of their first operations in C-Band spectrum last week, after delays resulting from interference with aviation altimeters. Verizon is pushing ahead with plans to build its network out in the C-band, having spent $45.45bn on spectrum there. With incentive payments and clearing costs bringing the outlay up to $52.9bn, Verizon understandably talked up the C-band as ushering in rapid growth on the mobile side, as well as disrupting the home broadband market via fixed wireless access. Meanwhile AT&T is expanding more modestly into the C-band, with operations beginning in parts of just a few major cities. The switch-ons come despite continuing anxiety on the part of some airlines. But hopes that concerns over…