The Librarian of Congress says its illegal to buy and unlock phones in the U.S. starting Jan. 26, but advocacy groups are questioning the law.

Starting Jan. 26, buying and unlocking a phone will no longer be legal in the U.S.

Although the Librarian of Congress, who determines any exemptions to a strict anti-hacking law called the Digital Millennium Copyright Act (DMCA), decided in October 2012 that unlocking cell phones would no longer be allowed, a 90-day window was provided during which people could still buy phones and unlock them.