The Federal Communications Commission (FCC) warns consumers of a recent wave of robocall fraud where a user's phone rings once before the caller.
The agency issued a warning last week about "One Ring" or "Wangiri" calling, calling on those targeted by fraud, not to call the numbers back.
"These calls are probably trying to ask consumers to call back the number, which often results in additional charges per minute similar to 900 numbers," the FCC said. "Consumers should not call these numbers back."
Robots can call the consumer's number several times, hoping the target rings back, the FCC said.
The FCC said the recent wave of calls seemed to be using the "222" country code of Mauritania in West Africa. Recent talks have been aimed at consumers in New York State and Arizona, the agency said.
In February, FCC released a report that found US phones were hit by 48 billion robococks last year. The report predicted that almost 50 percent of all calls made to US mobile phones this year will be spam.
Legislators have tried to fight the wave in robocols.
Sens. John Thune (RS.D.) And Sen. Ed Markey Edward (Ed) John MarkeySenate Dems requires FAA seat size update Group backing Green New Deal blasts Rourke's climate plan Senators require the FAA to allow remote tracking of drones MORE  (D-Mass.) Reinstated legislation earlier this year, called the "Telephone Robocall Abuse Criminal Enforcement and Deterrence Act", which would authorize the federal government to fines up to $ 10,000 per call.