I just bought a Nexus S on AT&T today (actually an exchange but w/e) and I have not been able to send text messages. I do everything but send messages, I can even receive them. I have tried changing the service code number by dialing *#*#4636#*#* and manually entering the AT&T service code number there. When I press update after I type it in, all it says in the box is error. All help is appreciated!