Feed Your Sense of Adventure.

"If there is one important bit of information to learn from reading this is that you need to be extremely sure of what plan you have before venturing off (overseas) with your phone. For example, almost all the main carriers, Verizon, Sprint, AT&T, and T-Mobile, offer affordable and even free roaming in Mexico. However, they also all have older plans that offer costly roaming rates. If you don't ask for the cheaper plans, they certainly are not going to volunteer it."