Cell phones - who has best offer

Good morning

I have been granted a year's overseas study scholarship at the University
of North Carolina starting in the spring semester 2014.

Rosemarie and I arrive in Greensboro NC on 26 December 2013.

I would like your advice as to what cell-phone provider to use and whether
pre-paid or plan is the way to go.

When we first arrive I imagine there will be heaps of local and
international phone calls but once we get settled Skype will take the place
of the international calls and there would be very few local or national
calls.

Thanks

Neville
Toowoomba
Queensland
Australia