How to transfer my service to a iPhone 5 from a family member?

My dad got the iPhone 6 and gave me his old iPhone 5s, but his number is still associated with the phone. How do I transfer my number and service to the new phone?

Have dad deactivate the phone from his account by calling customer care, and after that is done, you activate it on your account. This will automatically associate your phone number with the new phone.

This may not work if child has different cell service provider than father did (as in transferring from Verizon to Sprint)