Here's an advance look at a story I wrote for Wednesday's paper. The news is slated to be announced Wednesday at the CTIA Wireless show in Las Vegas.

AT&T says it will start using Microsoft Corp.'s Surface computers in selected retail stores later this month, becoming the first to roll out the Redmond company's tabletop machines.

The big U.S. wireless provider says its retail customers will be able to place specific mobile phones on Surface's 30-inch screen to learn about features, accessories and rate plans. They also will be able to compare two phones at a time, and use their hands to navigate a high-tech wireless coverage map.

As the first real deployment of Surface computers, AT&T's rollout promises to be a critical test of the technology, which uses optical sensors and a projection system to detect objects and display graphics. Surface has been slower to market than Microsoft originally predicted. People in the industry will be watching closely to see if the machines perform in the real world as they have in Microsoft's demonstrations.

AT&T says it's confident.

"We believe in Microsoft Surface and what it can do for our customers," said Andy Austin, AT&T director of retail customer experience. AT&T got "very, very excited" when it first saw the Surface computers, he said.

The first Surface computers will appear April 17 in AT&T stores in Atlanta, San Antonio, the San Francisco area, and two New York City sites. There will be several Surface units in each launch store, more than 20 in all. AT&T says seven stores will be added in May, in those same four markets.

AT&T wasn't among the original customers announced by Microsoft, and it initially won't be tapping the full promise of the Surface machines. For example, customers won't be able to finish their mobile-phone purchases on the tabletop computer. Microsoft's prototype applications were more complex -- showing, for example, how people could drag digital icons across the tabletop to order food and later split the bill at a restaurant.

"This to me is a fairly limited usage of the device. It's not all that exciting in some ways," said analyst Roger Kay, president of Endpoint Technologies Associates. "But they (Microsoft) know that they're late. They're very conscious of time slipping away, so if somebody has an application ready to go, it's like, 'Fine, let's go with it.'."

AT&T says it plans to add more features later, such as the ability to select ringtones, graphics and other features by dragging icons of them across the screen and virtually "dropping" them onto the mobile phone.

The company will use the initial deployments to see how customers and sales people use the Surface technology, Austin said. Although the timing hasn't been set, AT&T plans to ultimately use Surface as the "centerpiece" of its sales technology in all 2,200 company-owned AT&T stores.

By embracing the Surface computers, AT&T will have feet in two big technological camps. It's also the wireless provider and retailer for the iPhone, from Microsoft archrival Apple. AT&T says the Surface computers will be set up to work with eight different phones, but not the iPhone. The Apple device has its own kiosks in AT&T stores.

AT&T and Microsoft declined to disclose the financial terms of their arrangement. Microsoft last year said Surface machines might go for somewhere between $5,000 and $10,000 if sold as individual products, but terms tend to vary significantly in such corporate deals.

Microsoft received widespread attention when it unveiled the Surface machines last year. The company originally said businesses would start rolling out Surfaces in retail and entertainment sites last November.

The original customers -- including Starwood Hotels and Resorts, Harrah's Entertainment and T-Mobile -- are still on board, said Pete Thompson, Microsoft Surface general manager. The timeline for rollout is up to each of those companies, he said, explaining that some have taken longer than expected because they want to connect the Surface to their existing infrastructure.

"Just putting a unit in there with a standalone application was something that our partners decided not to do," Thompson said. "They wanted to wait until they had it integrated into the actual customer experience."

The company also plans to ultimately come up with a version of Surface for consumers. Microsoft executive Tom Gibbons recently told Fortune magazine that he envisions a consumer version within three years.

"We've got to get the commercial and the (business to business) product right, and we're staying focused on that," Thompson said this week. "But we are trying to accelerate our plans to get a consumer version out there, given the strong demand that we've had."

These are the AT&T retail stores where Surface will debut:

New York: 381 Madison Ave. and 350 Park Ave.

Atlanta: 3429 Lenox Road N.E.

San Antonio: 13127 San Pedro Ave.

San Francisco area: 1206 El Camino Real, San Bruno