Who’s calling now? That number doesn’t ring a bell. Hold the phone, says the Federal Trade Commission. You could be a potential victim of the growing “one-ring” cell phone scam.

Here’s how it works: Scammers are using auto-dialers to call cell phone numbers across the country. Scammers let the phone ring once — just enough for a missed call message to pop up.

The scammers hope you’ll call back, either because you believe a legitimate call was cut off, or you will be curious about who called. If you do, chances are you’ll hear something like, “Hello. You’ve reached the operator, please hold.” All the while, you’re getting slammed with some hefty charges — a per-minute charge on top of an international rate. The calls are from phone numbers with three-digit area codes that look like they’re from inside the U.S., but actually are associated with international phone numbers — often in the Caribbean.

The area codes include: 268, 284, 473, 664, 649, 767, 809, 829, 849 and 876.

If you get a call like this, don’t pick it up and don’t call the number back. There’s no danger in getting the call: the danger is in calling back and racking up a whopping bill.

If you’re tempted to call back, do yourself a favor and check the number through online directories first. They can tell you where the phone number is registered.

If you’ve been a victim of the “one-ring” scam, try to resolve the charges with your cell phone carrier. If that doesn’t work, file a complaint with the Federal Trade Commission and the Federal Communications Commission.

And as a general rule: Read your phone bill often — line by line. If you don’t recognize or understand a charge, contact your carrier.

Inc.com recently reported that there are actually three versions of this scam now:

Scammer calls and hangs up before anyone answers. Scammer waits for the victim to answer and plays a pre-recorded message of someone in an emergency situation and then hangs up. Scammer sends a text message indicating that they are in trouble.

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