T-mobile's pricing on plans and upgrade programs looks very enticing. They're the only carrier i haven't tried yet so i want to test them out before i commit to their program(s). I know there is typically a cancellation window (7-30 days) but would rather not deal with all that and possible fees that may include. Is that the only option?? Im currently on an open contract with Verizon iPhone 5S, so i couldn't use T-mobile's prepaid to try it out could i?