Got a call from these area codes? It could be a scam.

Earlier this week, Inc. reported on a scam that seems to reappear every few years, mostly thanks to the fact that it helps criminals steal people’s money. It goes by a few names – the “473 Scam,” “Ring and Run Scam,” or “One Ring Scam,” and the idea is to trick the recipient into calling  or texting back and charging them for premium services. The “473 Scam” name comes from the fact that these scammers use caller IDs with the area code 473. It appears to be a U.S. area code, but is actually for the island of Grenada! Scammers use international area codes with the +1 country code to appear as if they are calling from the U.S. in hopes that more would-be-victims will pick up.

The scam has a few variations:

1. Criminals call victims (usually using a robocall autodialer and spoofed number) and hang up before anyone answers to pique the recipient’s curiosity. They’ll often do this several times in a row, so when victims see the same unknown number over and over, they’re more likely to want to call back.
2. In another version, criminals don’t hang up quickly, but wait for the intended victim to answer the call. At that point, they’ll play a recording before hanging up. These recordings have been of someone crying for help, the sounds of someone needing medical attention or under attack. The criminals are hoping for a “Good Samaritan” to answer the phone that is more likely to call back and try to help. Some criminals may pretend to be a collection agency, law enforcement official, or doctor treating a relative.
3. In the third version, a criminal sends a text message similar to the cries for help in #2, making it appear the message was sent in accident to the wrong person.

So how to they get your money? Criminals can establish premium numbers similar to 900 numbers using the 437 area code and charge callers more than $20 per minute. If you receive a call like this, It’s pretty simple to protect yourself – just don’t call or text back. When you miss a call, the person calling usually leaves a voicemail or sends a text message to tell you why they called. If they do neither, it’s likely not necessary for you to call back and risk the charges.

According to the FTC, some of the area codes that have possibly been linked to the one ring scam include: 268, 284, 473, 664, 649, 767, 809, 829, 849 and 876. Inc.com has an extended list of area codes, including many in the Caribbean, on its website.