This is one of the simpler scams, but it has been around for at least a couple of years, which means it actually works.
Here is what happens: your phone rings one time, then stops. Curious to know who called, you use caller ID to call the number back and whoever answers tries to keep you on the line for as long as possible. Later, a charge for an international call and/or an extra charge for some kind of "service" gets added to your phone bill. Most of that money ends up going to the scammer.
And that is the entire scheme.
In the wave of one-ring fraudulent calls that hit in 2019, the calls came from the 222 country (not area) code, which is the West African nation Mauritania. Since most people don't memorize country codes, on first glance the number might just look like a regular domestic phone call. The FCC has detailed information available for download here.
The method for steering clear of this one is simple: do no go through your caller ID list and call every number back.
I have put that tip out a few other times, but usually in reference to calls that appear to come from a local phone number. In the case of these "spoofed local number" robocalls, the caller ID is NOT showing the actual number from which you were being contacted. Calling back would only end up with you harassing an innocent person.
In this case, the caller ID is not being spoofed, or at least, it is displaying a number the scammers want you to reach because that's all it takes to skim a few dollars from you. Some scams go for big hauls from a small pool of victims; this one is aiming for small gains from many.
