Stricter terms for the DMCA law went into affect today and prevents changes to cell phone carrier defaults embedded in the device (unless vendor offers capabilites as noted below)

http://www.nbcnews.com/technology/technolog/unlocking-cellphones-becomes-illegal-saturday-1C8086503

QUOTE: The clock to unlock a new mobile phone is running out.In October 2012, the Librarian of Congress, who determines exemptions to a strict anti-hacking law called the Digital Millennium Copyright Act (DMCA), decided that unlocking mobile phones would no longer be allowed. But the librarian provided a 90-day window during which people could still buy a phone and unlock it. That window closes on Jan. 26.

Unlocking a phone frees it from restrictions that keep the device from working on more than one carrier’s network, allowing it run on other networks that use the same wireless standard. This can be useful to international travelers who need their phones to work on different networks. Other people just like the freedom of being able to switch carriers as they please.

The new rule against unlocking phones won’t be a problem for everybody, though. For example, Verizon’s iPhone 5 comes out of the box already unlocked, and AT&T will unlock a phone once it is out of contract. You can also pay full-price for a phone, not the discounted price that comes with a two-year service contract, to receive the device unlocked from the get-go. Apple sells an unlocked iPhone 5 starting at $649, and Google sells its Nexus 4 unlocked for $300. [See also: Can I Get a Smartphone Without a Contract?]

Note that unlocking is different from “jailbreaking,” which opens the phone up for running additional software and remains legal, although it can be risky, for smartphones.