I'm really surprised at all the negative comments about AT&T Wireless. I've used AT&T for years - ever since they took over my original provider - and have nothing but great customer service from them. In fact, my military son had his own separate AT&T account with them when he was sent to Iraq last year, and when discontinuing his account I accidently over paid the final bill by $150 or so (so don't ask how - it's complicated!). Anyway, much to my surprise AT&T literally tracked me down to refund the overpayment - amazing considering I was doing everything in my son's name and not my own so they had no way of knowing I was a customer as well.
Then when I bought a tri-band GSM phone from a place off the internet and switched my service from regular wireless to GSM wireless, the AT&T service reps went out of their way to make sure I had the right simm card and all the useful hints and tips pamphlets that would have come with a phone bought from them. So far the only locale I've found where the phone hasn't worked was in St. Petersburg, Russia - and that was probably because I didn't have the right local access code with me.
All of this for a service for which I only pay $29.99 a month. Okay, I don't get miles for the $29.99 a month, but I do get good coverage and good service.