I bought a Verizon iPhone 4 off of Craigs list. It works fine and i love it but i can't use any other carrier on it other than Verizon since it does not have a Cim Card port. There are other companies that offer unlimited for around $50 a month and i do not want to pay versions crazy smartphone plans that are not even unlimited. What should i do/buy/trade to get an iPhone 4 that can be used on the cheaper unlimited carriers, And I'm pretty sure its hard to find someone that will trade the same iphone for different carriers. They usually just want cash.