Hello all, thank you for viewing my question. I was wondering, I am curious buying an iPhone for Christmas.. But, I have T-Mobile and have heard you cannot UNLOCK and Jailbreak a used iPhone that's already been used and activated for AT&T service, now is this true? Thank you guys and please I do not want any immature kids jumping in saying 'omg that is bad', if you have NOTHING TO DO with this QUESTION, please leave.