My dad and I are on a family plan (I'm 17) and he is eligible for a upgrade. I won't until December or January. I wanted to ask when (iPhone 5) comes out could I use his upgrade on the new phone? I just want to avoid paying 400 dollars. I have a job so I would give my Dad $199 for 16gb. He said if I can use it he wouldn't mind, as long as I give him cash for the new phone (which I already was planning to do).