AT&T has been criticized fairly for a long time for not being able to serve the Apple iPhone users in the US market. Their network is so congested in some areas that the iPhone fails to make calls properly. Users report frequent call drops.
One of the solutions to this problem is a 3G MicroCell which boosts the network signal in a limited area. AT&T usually charge for this product but is now said to be offering it for free to some customers. Reports say that these are being delivered to their loyal customers in areas where coverage is said to be problematic.