Who I have the same questioned this topic

it sounds like you want to do an Assumption of Liability (putting the phone into your name instead of your dads) this can be done 2 ways.  1.) at a corporate dealer.  2.) over the phone with customer service.  either way you are going to need both you and your dad available since your dad would need to authorize the realease of the line to you and you would need to accept terms and conditions of service and go through a credit check for verification.