I am one of the younger iPhone owners out there who lives in a community where these things would be stolen in a heartbeat. Me and my father agreed that if I got an iPhone, that I would also use one of his older phones to take to school/town at night. The clerk at the AT&T store said the best solution is to get a pre-paid plan for the older phone. I paid $150 for $1 for each day of use + $0.10 per minute. It didn't hit me till today. Could I have saved $150 by just switching out the SIM cards using the same iPhone plan on the other phone?