Hello, I'm fairly new to the Sprint CDMA world. Coming from AT&T where you simply pop in a SIM card into a phone and go, I'm not quite sure how it works on Sprint. How do I go about selling my phone or trading it with someone else? I'm currently under contract and I have a iPhone 5. Am I able to even do this or do I have to end my contract to be able to sell my device and use another? Thank you.