If you unlock your cell phone, you can change to a carrier other than the one through which you registered the phone.
…the U.S. Copyright Office and Library of Congress are no longer allowing phone unlocking as an exemption under the Digital Millennium Copyright Act (DMCA).
…in short, it is illegal to unlock a phone from a carrier unless you have that carrier’s permission to do so. If you’re wondering what this has to do with copyright, it turns out not much.
“It wasn’t a good ruling,” Rebecca Jeschke, a digital rights analyst at the Electronic Frontier Foundation (EFF), told ABC News. “You should be able to unlock your phone. This law was meant to combat copyright infringement, not to prevent people to do what they want to do with the device they bought.”
Of course, the carriers prefer the new rule because it ties your phone to their network.