The carrier is racing against rivals Verizon, T-Mobile, and Sprint to woo customers with the next generation of wireless technology that should be able to download data 10 to 40 times faster than current 4G LTE networks. A high-definition movie file that might take a few minutes to download on the fastest 4G networks would arrive in seconds over 5G.

AT&T said its new 5G service will be available immediately for use with a mobile Wi-Fi hotspot in parts of 12 cities, including Atlanta, Dallas, and New Orleans (see full list below). The network will be extended in the first half of 2019 to parts of seven more cities, including Los Angeles, San Francisco, and Nashville.

“This is the first taste of the mobile 5G era,” Andre Fuetsch, president of AT&T Labs and the carrier’s chief technology officer, said in a statement. “Being first, you can expect us to evolve very quickly. It’s early on the 5G journey and we’re ready to learn fast and continually iterate in the months ahead.”

At first, the 5G network will be available free for at least 90 days to “select” businesses and consumers, AT&T said. In the spring, all customers in the 5G regions will be able to buy the compatible Netgear Nighthawk 5G Mobile Hotspot for $500 and sign up for service.

But there won’t be unlimited data plans, at least at the start. Service will cost $70 per month for 15 GB of data. Customers using the new network for big data jobs could smash through that allowance, equal to four or five HD movies, pretty quickly.

AT&T (T) didn’t say much about customers using phones instead of a hotspot on the new 5G network. The carrier has previously said it will offer at least one 5G-compatible phone from Samsung in the first half of 2019.

The $70 monthly price is for access through the hotspots only, a spokesperson said. “We’ll share more about smartphones in the first half of 2019,” she said.

Verizon (VZ) hasn’t released detailed plans and pricing for mobile 5G. It is already offering a home broadband Internet service, which connects nearby devices through a home router via 5G in parts of four cities, Sacramento, Houston, Los Angeles, and Indianapolis.

T-Mobile (TMUS), which is merging with Sprint (S), says it’s building 5G mobile service in six of the 10 largest markets, including Los Angeles and New York, with plans to have a nationwide network ready in 2020. Sprint recently announced a 5G service using a “mobile smart hub” coming in the first half of 2019 to nine cities, including Chicago, New York, and Washington, D.C.

Cities Getting AT&T 5G

Initially: Atlanta, Charlotte, N.C., Dallas, Houston, Indianapolis, Jacksonville, Fla., Louisville, Ky., Oklahoma City, New Orleans, Raleigh, N.C., San Antonio and Waco, Texas.

First half of 2019: Las Vegas, Los Angeles, Nashville, Orlando, San Diego, San Francisco and San Jose, Calif.