I've got a buddy that works at a cellphone store that carries various companies such as AT&T. According to him, AT&T - and other cell phone service providers - do a "network sweep," that checks to see the data plan the customer has, and the device using the service. If the two do not match up, AT&T will update the customer to the correct plan so as to meet the device.
If that is the case, then wouldn't my plan be changed automatically by them.
Sorry for the questions, but this is interesting and i'm really not phone-savy.