T-Mobile has announced another expansion of its 2.5GHz midband 5G network, which is now available in dozens of new cities, nearly doubling the coverage of its last major midband rollout from the end of September. With today’s expansion announcement, T-Mobile says that it now has midband 5G support in nearly 410 cities and towns in the United States.

The new expansion comes just after the launch of Apple’s new 5G-compatible iPhone 12 lineup, which is expected to vastly increase the number of 5G devices in the US.

T-Mobile’s 5G network combines its widely available 600MHz low-band network (which offers coverage on a nationwide scale but not much in the way of speed improvements of LTE) with the faster 2.5GHz network (which it acquired from Sprint) along with its ultra-fast mmWave network (which has the best speeds but the worst range).

It’s what the company likes to call its “layer cake” approach to 5G, with the 2.5GHz chunk of the cake the “Goldilocks” portion: fast enough to offer a meaningful speed increases over regular LTE and low-band 5G but still able to be transmitted over broad chunks of cities and towns without worrying about interference from trees, walls, or buildings (problems that greatly limit mmWave).

T-Mobile already has wide nationwide coverage on its low-band network, thanks to its initial 5G launch last year. The goal of the current midband expansion is t