Q: Registering iphone

I have a second hand iPhone4 which was given to me by a relative. When I took over the phone I did a total reset then set it up to synchs with my icloud account, but it does not register in my AppleID. Also I am unable to link the phone to my imessage or FaceTime emails I use on other devices. Lastly when I enter the phone's serial number in to my Apple ID I get a message saying it is registered to another email. How can I reset the registration?