Last October, it was determined that effective on January 26th, 2013, unlocking a mobile phone (different from “jailbreaking” which means opening a smartphone and running additional software) is no longer allowed under the strict anti-hacking law Digital Millennium Copyright Act (DMCA.)  Unlocking a phone essentially removes the restrictions of the smartphone only working on one carrier’s network.

This is not a problem if you’ve asked your carrier first.  Nor is it an issue if you buy a phone outright full-price (without a contract) and receive it unlocked at the time of purchase (such as the Verizon iPhone 5.)  Nor is it a problem for AT&T users that have AT&T unlock it once it is out of contract. 

What this boils down to is that only a consumer, who is ALSO THE OWNER OF THE COPY OF SOFTWARE on the handset, may lawfully unlock the handset.  This could be bad news for T-Mobile who advocates customers bring their own device.