I was wondering how the unlimited data is tied to your account? Is it via the SIM card? Because I had an old 3G iPhone on unlimited data that I stopped using when the 4 came out. I upgraded to a 4, and then a 4S in the fall of 2011. When I upgraded to the 4S, my dad decided he wanted to try out a smartphone, and decided to use my old 3G. By this time, AT&T had stopped giving out their unlimited data plan. However, when we "re-activated" my old 3G, I was surprised that we were able to have the unlimited data on both the 3G, and MY current iPhone. Does anyone know why this was possible? I am about to go overseas for a year or more and was going to cancel my AT&T subscription while I am away.... however, I fear that I will lose my unlimited data plan forever. Anyone know why I was able to get the unlimited plan on my old 3G after it was sitting around for over a year on no AT&T plan???? Thanks.