I have an iPhone 5 that is malfunctioning, and it's getting worse. I am hoping the phone makes it until the new iPhone 6S is released, but I am doubtful. This is my only phone and I also use it for business, so I was wondering if I could get a cheap phone to use as a backup in situations like this? My service is thru AT&T and there is a SIM card in it. Is it as easy as buying a cheap phone and popping the SIM card in? If so, where could I get a cheap phone? A flip phone would be fine, if it will work with my SIM card.