So that's half the problem - the other half is the locked handsets. With TMobile, you pay for unlocked you get a fully unlocked handset. If you are on the TMO installment plan, your phone is locked until you pay up, at which point they unlock it - no 2 years required.
Last I heard (6 months ago), AT&T makes you wait till your contract is up before unlocking, and on the other side Verizon won't let you bring your unlocked phone to their service - forcing you to buy one from them.
