Mobile phone questions?

I am traveling to Cuzco, Peru at the end of the month and I will be staying for about four months. I would like to purchase/rent a moblie phone for the duration of my stay. I would like to make and recevive phone calls to the U.S.A and I would like to make/receive calls to numbers within Peru. I am looking for the most affordable option, and I do not require anything too fancy. I am not sure how the moblie service works down there, but I think that doing some sort of pay as you go type of thing would be the best, as there is really no way for me to recieve and pay a monthly bill. Please fill me in on any tips about figuring out this whole moblie phone dilemma. Thank you. Reply to this