A new phone scam is sweeping the country.

Part of what makes it dangerous: Crooks don't even need your credit card information to steal your money. All they need is for you to return their phone call.

Food writer Jenny Vergara was hard at work around lunchtime recently when her cell phone rang once.

"I looked down at the screen and I realized it was this weird Antigua call and I thought, don't know anybody in Antigua," said Vergara.

She didn't know it then, but Vergara had just become the target of an international phone scam.

Scammers overseas buy or steal lists of U.S. cell phone numbers and use computers to mass dial them.

Your cell phone rings just long enough to generate a missed call.

When you call back, the spammers charge your bill like a 900 number. They charge $20 for the call and another $9 for every minute you spend on the line.

"It is a new take on an old scam, so we are familiar with this type of thing, but the one-ring scam is brand new," said BBB spokesman Aaron Reese.

The Better Business Bureau says this scam is more effective than some others -- in part because it raises no red flags.

"There is no one trying to sell you anything. There is no one sending the wrong type of message or who has a foreign accent or doesn't speak very well. All of those things that we look for are absent," said Reese.

Even the number looks normal, aside from where it came from. For many smartphone owners, the unfamiliar location was the only warning they needed not to return the call.

"So it said, 'Antigua' and I thought, yeah, no. I'd like to go visit there, but I don't know anybody there," said Vergara.

Experts say scams like this normally target one region or city at a time.

The BBB says part of what makes this one different is that it's happening all across the country and all at once.