AT&T and Verizon are expected to be first out of the gates with service by the end of 2018, but T-Mobile is clearly betting that this won't matter to most people until months later, when you can use it away from a computer or tablet and coverage is more consistent. And there's a degree of truth to that. When AT&T announced its first 5G cities, it tacitly acknowledged that you'd have to wait until 2019 for the coverage and devices you would prefer. Sprint is aiming for 2019 as well. In other words, much of the talk about 2018 (T-Mobile's included) is more about shouting "first!" than fulfilling promises.

The real challenge is providing good 5G service. T-Mobile may have an edge through its relatively untapped 600MHz network, which promises longer range and better overall coverage even compared to the 700MHz space used for LTE today. Those airwaves will only be usable in some places, however. It's up to providers to deploy enough cell sites and capacity to ensure that 5G has the coverage and breakneck performance you expect.