Re-activating my returned stolen phone
My iphone was stolen from my work and I had reported it stolen to Sprint and had my phone deleted of everything and wiped clean. About a month later I had recovered my phone once again at my work. I had already used the insurance and paid for a new phone. I would like to re activate the old original phone instead of using the refurbished phone I was sent. I tried to change out the SIM card but I am not sure that Sprint uses the SIM cards as other carriers do because it only allowed me to get through logging into itunes and stopped me when I was trying to update my last back up from icloud.
Would anyone have any advise on how to reactivate my old iphone and complete the restoring process. I have a feeling I am going to need to either contact sprint or Apple to have this phone "unflagged" stolen.
iPhone 6 Plus, iOS 9.2.1