AT&T's 3G MicroCell uses your Internet connection to act as a mini 3G tower—something iPhone users in particular have waited for. And after reports it could arrive in select locations this week, AT&T is now providing (some) details:
You can register up to 10 phones (3G models with AT&T accounts) to work with the device, but it only supports four simultaneous calls or data sessions. It has a roughly 5000 square foot range, and calls originated from it are automatically handed over to AT&T towers once you leave the house/office.
The MicroCell page also confirms an unlimited calling option where domestic U.S calls made using it won't deduct from your regular minutes. Problem is, AT&T hasn't coughed up what the pricing will be. An apparent leak over the weekend suggested it could be $20 per month ($10 if you have an AT&T Internet or landline service; free if you have both). No word yet on how much the device itself might cost.
Travelers will be sorry to hear that, as with Sprint and Verizon did with their femtocell units, AT&T's device has a GPS chip, so it can't be used out of the country. For that reason it's recommended to be placed near a window.
You'll need to have a net connection of at least 1.5Mbps down/256kbps up, and find your ZIP code in the availability checker at the site. Please let us know if you find your area is listed.
Also See: Should Users in Known Dead Spots Get the MicroCell 3G Free? [AT&T 3G MicroCell Site | 3G MicroCell Manual (PDF) | via @bugdave]