Ok so when the new iPhone is released I'm breaking my contract from AT&T and switching to Verizon. I know when I port my number, it will instantly cancel the AT&T contract. To anyone who has canceled a contract before, how long did you have to pay it? Lets say if the rumors of Sept. 12th preorder date, Sept. 21 release is true, if I preordered it immediately, whats my window to pay off AT&T? Thanks.