I actually bought an evo off of Craigslist about a month ago, and all you have to do is call sprint, from a different phone and direct yourself to activations. There they will ask your information, then tell them which number you will be activating, they will ask for the esn of the new phone and that's pretty much it. You dnt have to mention anything about your current phone, they don't care, all they care about is keeping your business pretty much lol oh and yes, it'll be free of charge.
P.s. be careful on Craigslist. Make sure the esn of the phone is clear. I'd advise to ask the owner for the esn then call sprint to verify if its clear.
