The White House has responded to the over 100,000 petitions for unlocking cell phones. It supports unlocking of cell phones that are paid for and free from a contract. The President will work with the FCC and NTIA to help clean-up laws so that it is not longer a criminal offense to unlock the phone you own.
The White House stated that it "agrees that consumers should be able to unlock their cell phones and tablets without risking criminal or other penalties. "
If you have paid for your mobile device, and aren't bound by a service agreement or other obligation, you should be able to use it on another network especially secondhand and gifted phones, noted the statement from R. David Edelman , Senior Advisor for Internet, Innovation, & Privacy.