The Federal Communications Commission has ordered phone companies to stop carrying traffic related to robocalls about scam auto warranties. US voice service providers must now “take all necessary steps to avoid carrying this robocall traffic,” or provide a report outlining how they’re mitigating the traffic, they said in a statement on Thursday. Via Bloomberg:

The group appears to be responsible for making more than 8 billion unlawful prerecorded calls to Americans since at least 2018, per the FCC statement. The operation is also the target of an ongoing investigation by the FCC’s Enforcement Bureau and a lawsuit by the Ohio Attorney General. Auto warranty renewal calls were the top robocall complaint filed with the FCC by consumers in 2021. The number of complaints filed with the FCC about auto warranty scams rose from close to 7,600 in 2020 to more than 12,000 in 2021, the agency said.

The calls often include specific information about your particular car and warranty that can make the call seem more legitimate, according to the FCC. Other top categories for robocalls were Social Security number phishing scams, credit and credit card scams, fake insurance and healthcare, and phony lawsuit or criminal charges, the FCC said. Americans received over 4.3 billion robocalls in June, marking an 8.5% increase from May, according to a tally by YouMail Inc., a developer of software that blocks the calls. Because May has one more day than June, robocalls were actually up 13.4% on a daily basis.

The FCC in recent years has told carriers to adopt a system to digitally validate phone calls passing through the complex web of networks that carry phone calls. The agency also has made it clear that providers may block calls. And in May, the agency adopted new rules to stop illegal robocalls that originate outside the US from entering American phone networks.