I would like to get an iPad Air. I currently have an iPad 3 with a grandfathered $30 unlimited AT&T data plan that dates back to the original iPad. The iPad 3 has a micro SIM, so I won't be able to just transfer the SIM to the new Air. Does anyone know if it's possible to keep the old data plan? How does the setup work for cellular data when moving to a new iPad? I have had bad luck in the past with the people at the AT&T store messing up phone plans. I'd rather know the procedure in advance, and I'd prefer to avoid involving the AT&T reps as much as possible.