Excellent ATT warranty service
I actually had a good experience with an ATT mobile service that I want to publicize. This is a service in the SF Bay area (I don't now how it is in other regions). If you have a problem with your phone while it is under warranty and you are an ATT customer there are stores that provide warranty service on the phone at no charge. They do this independent of where you bought your phone. All you need to do is go to one of the stores -- they will determine the problem with your phone and they will either fix the problem, replace the phone, replace the battery etc. They may not have the part at the store but in my case they shipped the new part out in 2 days. Look for ATT Device support centers on web.