WashingtonCNN Business —

No sentence in the English language may be more infuriating than the following 12 words: “We have been trying to reach you about your car’s extended warranty.”

If you’ve picked up the phone in response to an unknown caller anytime in the last several years, chances are you’ve encountered this incessant and irritating automated message. But according to state and federal officials, just two men may be responsible for an overwhelming share of the billions of auto-warranty spam calls that have hit US phones.

Now, a new lawsuit in Ohio is trying to cut them off at their source, following a years-long effort across the public and private sectors to turn the tide on the scourge of robocalls once and for all.

In a complaint filed last month by Ohio Attorney General Dave Yost, the ringleaders of the auto-warranty robocall scheme are identified as Roy Melvin Cox, Jr. and Aaron Michael Jones, two California individuals described as repeat offenders of US telemarketing rules...