to unlock an iphone on sprint you do not need a phone active on sprint. the cell phone code says that phones that have fulfilled their contract and left their account in good standing can get it unlocked to be used on another local carrier. sprint says they will only give you a worthless msl for your 4s/5 with everything required to get it unlocked met. call fcc, ctit, or consumer protection agency through your state attorney office.
i have contacted the fcc , sprint the attorney general, consumer protection agency and several others. they are suppose to unlock as you have stated as of feb11,2015. the msl code is of no use. if you want to use locally you are out of luck with sprint. they are defiant. if you get yours unlocked please let the rest of us know.