I am going to China on February 16. I have a IPhone 4S on Verizon. What is the cheapest way to make calls both within China to a friend I am going with and communicating back home? My friend suggested I buy an unlocked $100 Nokia phone on Amazon and buy the sim card when we get there and it will be less expensive. Can I buy a card over there that will fit in my iPhone? I do want to be able to check my voice messages a couple times a day. Thanks for anyone's help and suggestion.