As many as 525 million 5G handsets will ship in 2023, up from 37 million this year, according to a new forecast from the UK-based IHS Markit information service.

It says that 5G handsets will outpace initial LTE devices by a factor of six, making it the fastest cellular rollout ever.

About 10 US cities already have 5G services, with another 10 coming online by the end of the year.

“I’ve upgraded my forecast for 2019 from about 11 million to nearly 37 million 5G handsets, due to the fact that there are more than 20 5G smartphone designs that OEMs are pushing out,” said Wayne Lam, a smartphone analyst for IHS Markit.

So far, Huawei, LG, Motorola, Samsung and Xiaomi have announced or shipped 5G handsets.