A close friend of mine (after stating I have the new iPhone5S) asked if I still had my old iPhone. I said I actually have 2 (a 4 and a 5). He asked if he could buy either one from me and give to his daughter as an iPod for the time being and then a cell phone later. I said sure, I'd just give him the iPhone4 but that I need to do some research first as to what I need to do to make sure it can be used fully functional except the cell phone portion. So.....is there a guide, instructions, etc, that can direct me to what I need to do so I dont' screw this up?