T-Mobile finally began selling the iPhone 5 early on Friday, and it seems as though all that pent-up consumer tension has resulted in some promising sales for the carrier. “Today has been gangbusters for T-Mobile,” CMO Mike Sievert noted to AllThingsD. Naturally, Sievert wouldn’t discuss just how many iPhones were moved during the course of the day, but he did point out that customers had lined up at “nearly all” of the carrier’s retail outlets. By now the iPhone 5 is a known quantity so most stores didn’t see the sort of crazy volume that usually goes with an iPhone going on sale — for what it’s worth, our intern Michael only noticed a handful of people waiting in line at a T-Mobile store near our office in New York’s Lower East Side — but it’s heartening to see those customers finally getting a chance to pick up an iPhone without having to switch providers.