AT&T Inc. is moving its headquarters to Dallas from San Antonio, the telecommunications company said Friday afternoon.

AT&T said the move will start immediately and be completed by the end of the year.

The company will be moving to existing AT&T offices at 208 South Akard St. in downtown Dallas.

That won’t necessarily be AT&T’s permanent home in the Dallas area, though.

“We’re continuing to evaluate our long-term real estate needs in the Dallas area,” said AT&T spokesman Walt Sharp.

About 700 of the company’s nearly 6,000 San Antonio-based workers are expected to move as well.

Those workers making the move are mostly corporate staff, with the technical positions remaining in San Antonio.

AT&T, now the largest telecom company in the world, said the move to Dallas makes sense in light of the company’s growth.

"We're a growing global company with customers and operations around the world," Randall Stephenson, AT&T’s chairman and chief executive officer, said in a statement.

"Being headquartered in Dallas will benefit our long-term growth prospects and human resources needs, and our ability to operate more efficiently, better serve customers and expand the business in the future.”

AT&T will also benefit from the concentration of telecommunications engineers and experts and the cluster of tech firms based in the so-called Telecom Corridor area in Richardson.

AT&T is the most recent big telecom firm to bring its headquarters to the Dallas area.

Last December, Research in Motion Ltd., the Ontario-based maker of the popular BlackBerry mobile e-mail device, chose Irving for the site of its new U.S. headquarters.

Dallas mayor Tom Leppert said Friday that AT&T had been in discussions for about a year to move to Dallas, but it wasn’t clear until the past few days that the relocation was certain.

“It’s a great victory,” Mr. Leppert said. “It’s absolutely a big deal. It shows that downtown Dallas is a great place to work and this is a great place to live.”

Mr. Sharp said that AT&T had 60,000 employees when it moved to San Antonio in 1992, and now has about 310,000 workers around the globe, while revenue has grown from less than $10 billion to nearly $120 billion.

By revenue, AT&T will be the second-largest company based in the Dallas-Fort Worth area behind Exxon Mobil Corp.

When the move is complete, AT&T will have about 14,400 workers in the Dallas area.

AT&T is making the move as it gears up for the exclusive launch of Apple Corp.’s much anticipated new iPhone on July 11.

Staff writer Dave Levinthal contributed to this report.