Poor service, poor customer relations, AT&T just doesn't get it
I have 5 3G iPhones in a family plan. This is a minimum $360/mo financial commitment. You'd think for that kind of money you'd get good phone service and excellent customer service. Think again. In any area where AT&T is not the primary provider, cell service is intermittent at best. Two identical iPhones side by side can show vastly different signal strength. Calls either don't go through or are dropped within seconds. Messages fail to appear for hours. After many hours on the phone to them, I've determined that their technical support is worthless. They don't even acknowledge a problem, let alone know how to fix it.
Better yet, provision of poor service is not an acceptable excuse to relieve you of your sign up contract obligations. If you want to switch to a service that works, prepare to pay a huge early termination fee or pay for duplicate service with another company.
Apple chose the wrong cell partner. It's a sad thing, but AT&T is ruining the iPhone experience for this particular user and his family. If I could do it over, I'd choose another smart phone and a different cell company. Unless you live in a major metro area, run, don't walk, to any provider but AT&T.