I'll be spending six months in the U.S. this fall/winter, and want to purchase a cell phone on a prepaid plan once I arrive. I do need to be able to receive and call overseas on the cell, along with calling back home to Canada. Any opinions or comments on the cell phone providers I should be looking at that give me the best price? I have started researching all the different cell phone providers and am a bit overewhelmed by the selection