Almost eight years ago, the U.S. Copyright Office gave cellphone owners the right to unlock their cellphones. It had been illegal since the 1998 Digital Millennium Copyright Act (DMCA), which banned the “circumvention” of any copy protection mechanisms (Section 1201).
This did not, however, mean that carriers honored the ruling.
AT&T, for example, has been a notable laggard with regards to the iPhone. From April 2012 :
In a statement to Phone Scoop, AT&T said that it will [finally] offer customers the option to unlock their iPhone so long as they’re not currently under contract and have an account that’s in good standing.
Last January, the rule changed: If you bought your cellphone after January 26, 2013, you could unlock it only with approval from your carrier. Even if your contract has expired, ostensibly after the phone is “yours.”
On July 25, the U.S. House of Representatives passed S517 on a voice vote; the bill is designed to “promote consumer choice and wireless competition by permitting consumers to unlock mobile wireless devices.” The bill had passed the Senate on July 15 by unanimous consent.
However, the term of the bill is limited until the next scheduled review by the Copyright Office in 2016.
As I pointed out last year, unlocking and jailbreaking are not the same thing. An unlocked phone can be used on a network other than the original carrier. Jailbreak your iPhone if you want to install third party apps.