T-Mobile’s 5G network is now up and running in several US cities. This initial phase of the carrier’s 5G strategy uses the same sort of high-frequency millimeter wave network tech as Verizon, resulting in download speeds that far exceed what LTE phones can reach today. The biggest problem with millimeter wave is range: to cover a whole city, you need to have 5G nodes—the things that beam out the millimeter wave signal—all over the place. In Verizon’s case, things are still spotty. As I keep saying, 5G speeds are there on one street and gone the next. Walls and windows are also fatal for millimeter wave, so it doesn’t extend indoors.