AT&T on Wednesday announced three of the 12 U.S. markets that will be part of its initial rollout of mobile 5G service later this year.

The telecom giant said parts of Atlanta, Dallas and Waco, Texas, would see the service by the end of the year.

The company houses its wireless operations in Atlanta and is headquartered in Dallas — and recently concluded 10 Gbps XGS-PON field trials in those cities. Waco, meanwhile, was home to its largest 5G fixed wireless trial to date late last year.

AT&T plans to use millimeter wave spectrum to initially deploy mobile 5G before adding service on additional spectrum bands. Additional cities targeted for mobile 5G in 2018 will be announced "in the coming months," officials said.

"After significantly contributing to the first phase of 5G standards, conducting multi-city trials and literally transforming our network for the future, we’re planning to be the first carrier to deliver standards-based mobile 5G," AT&T Wireless Network SVP Igal Elbaz said in a statement. "And do it much sooner than most people thought possible."

The company also announced the opening of a new 5G lab in Austin, Texas, that will enable engineers to test equipment, devices and applications. The facility includes the company's proprietary Advanced 5G NR Testbed System, which re-creates "a physical 5G radio environment in our labs."

"ANTS will let us test unique and forward-looking features on a simulated 5G network for eventual standardization and use on our commercial network," company officials wrote.