I'm on AT&T right now, and have a HTC HD2 running Android 2.3.1, and it works flawlessly on the network. Nation wide calling, no roaming, data everywhere I want it - what more could I ask for? It is good enough that I switched over my home stuff to U-verse last week. Now everything is seemless, and I can even watch my recorded shows on my cell. Whatever you do, go with Android for the phone OS - better than iPhone by far.