I just upgraded to an iphone and I am going to Jamaica next week for spring break. I am worried that there are 100 possible ways for me lose/break my new phone. Can I just take out my sim card and put it back in my old phone and use it during my trip and put it back in my iphone a week later and have it work perfectly? Also, if I do end up losing my backup phone can I just go get a new simcard at the AT&T store? Thanks!!!!