I know T-Mobile technically does not allow this in many cases though. I did once talk to a customer who bought an unlocked 1G iPhone from a dealer with a 2 yr contract for about $500 he said. If T-Mobile found out these stores were doing this, they could get into trouble. With regards to the myFaves, it is not phone dependent for billing purposes, but as stated earlier you would need to use the web to manage contacts. However, if you call care to sign up, a good rep would check and see you don't have a myFaves phone and we can't sign you up. You would in that case want to lie and say you are using a different phone that is myFaves because I'm not allowed to give you a myFaves plan if you don't have the phone. The reason for this is to minimize user error. People would call in and say they thought someone was in their myFaves and wasn't or thought they had changed it when it didn't go through. When it shows up on your phone, it minimizes confusion.