So basically I would be paying $100 for a t-mobile contract phone, $200 for the etf, making it a $300 phone, which is $250-$300 cheaper than I've been seeing it elsewhere to pay for it in full. The thing is, once I cancel the contract (I'd do it after having it for one month by the way), I would want to stay with t-mobile on one of their prepaid or value plans. I understand there may be some extra fees involved like taxes or activation or new sim card, but even then it would only come out to about $400 right? What is it exactly that would stop someone from doing this? Other than the ethical implications of course. Would t-mobile prevent me from doing this? If not, why does this loophole exist?