Are the phones locked?

Due to financial difficulties my wife and I are leaving Verizon a little early ( just a few months) and shaving our phone bill in half by swapping to Tmobile. We have had a lot of issues with Verizon, and despite the phone service being good, the actual customer service from them was less then desireable. They really need to work on this big time.

We are going to pay Verizon, but it might be in smaller chunks then all at once. We are hoping to offset this by selling the phones we have to help pay for it. Does Verizon lock the phones from getting a new owner until paid off or not?

Please don't rag on me for having to end my contract by force, we will pay this off, but we just needed to know if we could sell the phones or not.