I was wondering if, when I upgrade to iPhone 4, I will have to pay the 1 month advanced payment of my bill? When I started my contract, and when I added a line in the past, I had to pay a prorated amount for the month, plus the full bill for the following month (however, I still get billed every month, so if I cancel my service now, shouldn't I not have to pay my bill that's due next week?). I was wondering because I want to make sure I have the correct amount of money when I go and get my phone.