Verizon in April became the first U.S. carrier to offer 5G service via a phone, though the phone in question was a Motorola model with an ugly 5G add-on pack. Reviewers measured download speeds as high as 600 megabits per second, 10 to 20 times faster than on a typical 4G LTE network. And Samsung’s much slicker (and lighter) Galaxy S10 5G model is coming out any day now.

But the problem for Verizon’s 5G service, and a similar offering also due soon from AT&T, is limited coverage. Very limited coverage. Verizon started in Minneapolis and Chicago but only in a few neighborhoods in each city. And because Verizon and AT&T are using high wavelength bands for 5G, the signals don’t travel as far as current day cellular networks.

PC Magazine analyst Sascha Segan walked around the one tiny part of Chicago where Verizon turned on 5G service and found speeds plummeted when he got more than 300 feet away from a cell site–or when he just walked around the corner of a stone building. Verizon says it is planning additional technological fixes that will extend the range. And it’s connecting 30 or more cities this year, at least in some neighborhoods. AT&T says it’s built out 5G for 19 cities.

Nationwide coverage is a year or more away. Rivals Sprint and T-Mobile may get better coverage with their 5G services, coming later this year, that don’t rely on the high airwaves bands, but probably won’t attain the same speeds, either. So for most consumers hungry for super-fast mobile downloads, it’s still hurry up and wait.

This article originally appeared in the June 2019 issue of Fortune.