Federal Communications Commission Chairman Ajit Pai told major telecommunications providers today that the agency would step in if the companies failed to implement a plan to fight robocalls this year.

In November, Pai sent letters to several companies, asking them to use a caller authentication system to battle call spoofing, a technique robocallers use to imitate other numbers. Pai’s letter said he expected the companies to implement the plan by the end of this year, and also said that the agency would “take action” if carriers didn’t follow the plan.

Pai previously said the FCC may “take action”

The companies have now responded, although the agency isn’t pleased with what they have to say. Some of the companies suggested they would need more time than the end of the year to completely implement the system Pai wants. AT&T, for example, said it was “fully committed to this innovation,” but that “significant work remains.” Its response said its implementation plan would stretch into 2020.

In response, Pai released a statement today criticizing the responses from some of the companies. “It’s time for carriers to implement robust caller ID authentication,” Pai said in the statement. “Uniform adoption will help improve authentication throughout the network and make sure no consumer gets left behind.” If major carriers fail to implement a plan this year, the statement said, “the FCC will have to consider regulatory intervention.”

Pai has repeatedly said that cracking down on robocalls is a priority of his tenure leading the agency. Lawmakers have also pressed legislation. In November, a group of senators promoted a bill that would give the FCC more power to impose higher fines against robocallers.

“American consumers are sick and tired of unwanted robocalls, this consumer among them,” Paid said in the statement. “Caller ID authentication will be a significant step towards ending the scourge of spoofed robocalls.”