I'm going out of the city for a night to Orlando. I have an iPhone and I don't want to take it just in case I lose it because I'll be going to Universal Studios for a class trip. I have an old Palm Centro that I have that used to be my old phone. Is it possible that I can just switch my SIM card from my iPhone to the Centro and use the Centro for just one night and not have to worry about any charges?
You likely will be able to put your sim in another phone and be good to go. Try it before you leave and see. You will not be able to use the data side. My past experence has been that I did not need to contact AT&T to switch to a backup phone.