The test of the MicroCell is currently taking place in Charlotte, N.C. Up to four simultaneous users can get what the company described as "improved cellular signal performance" of up to five bars within 5,000 square feet from the device for voice and data.

Compatible with 3G Phones

AT&T said the device is compatible with any of its 3G phones, and is secure so that a data signal cannot be accessed by unauthorized users. There is also "seamless call hand over," allowing a user to begin a call with the MicroCell, and the call can continue even if the user leaves the device's signal area.

A user registers the MicroCell and can manage the device settings via a networked computer . While the device can be moved, it needs to be set up within AT&T's service area and has to be registered online. Installation near a window is recommended, since a Global Positioning System (GPS) signal is required for verification during setup.

The MicroCell is a femtocell, which is a small cellular base station that allows a user to extend phone coverage by tapping into a broadband connection. The conversion could be to various data standards, not just 3G. For instance, femtocell devices are also available from Verizon Wireless and Sprint Nextel, although neither supports 3G.

According to news reports, the price for the MicroCell will be about $150 when it becomes generally available, with no charge for the service itself. Unlimited talking is expected to be $20 per month, plus a rebate on the MicroCell.

'Throw Some Price Points Out'

Verizon and Sprint are also offering a device called MiFi, which takes a 3G signal and turns it into Wi-Fi for simultaneous computer users. With these kinds of translations between high-speed Internet for computers and 3G for smartphones, are the differences between the technologies getting blurred?

Peter Jarich, an analyst with industry research firm Current Analysis, said MiFi is "more for when you're out in the world, on the road" and need a Wi-Fi setup for a variety of computers, whereas MicroCell and similar devices are more for a single office or home where better 3G reception for a cell phone is needed.

"They're different markets," he said, adding that it's "still early" in the development of devices such as the MicroCell and the price points are relatively high.

Bill Ho, also a Current Analysis analyst, said a key point of the North Carolina trial is to "throw some price points out and see what takes." On its Web site, AT&T indicates that a rollout is anticipated, as the site allows a visitor to sign up to a mailing list to find out when the MicroCell is available in given areas.