Wireless carriers need to agree to let consumers unlock smartphones or face U.S. regulations mandating the change, the chairman of the Federal Communications Commission (FCC) said.

Unlocking alters software so a phone can be used on a competitor’s network. The practice of unlocking was ruled a copyright violation in a ruling from the Library of Congress that took effect last year.

“It is now time for the industry to act voluntarily or for the FCC to regulate,” Tom Wheeler, the Democratic chairman of the agency, said in a letter Thursday to Steve Largent, president of CTIA-The Wireless Association.

Wheeler proposed having a policy in place “before the December holiday season.”

Members of the Washington, D.C.-based trade group include the four largest U.S. carriers led by Verizon Wireless and AT&T.

“We look forward to continuing discussions under Chairman Wheeler’s leadership,” Scott Bergmann, CTIA vice president, regulatory affairs, said in an emailed statement. The group supports an unlocking bill that is before Congress, Bergmann said.