It starts with an incoming call from a number you don't recognize. Your phone rings once, then the caller hangs up.
If you call the number back, you'll probably be greeted with a recording that asks you to hold for an operator or a similar message. But the 10-digit phone number you just dialed isn't a U.S. number; it's an international number that charges by the minute — much like a 1-900 number — and that's on top of the international fees your carrier charges.
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It's called the "one-ring" scam, and has become increasingly prevalent in recent weeks, according to the U.S. Federal Trade Commission.
To help users avoid falling victim to these scams, WhitePages rolled out an update to its Current Caller ID app Tuesday that alerts them to phone calls made or received by scam numbers.
"This is an issue that has plagued the U.S.," WhitePages CEO Alex Algard told Mashable. "We're really excited to be combating the bad guys."
The free app relies on WhitePages' database of more than 20,000 suspicious phone numbers to track calls that are likely linked to one-ring scams or other fraudulent activity. Algard said these numbers typically originate from the Caribbean, and use auto-dialers to make many calls at once.

WhitePages' Current Caller ID app now alerts users when they make a receive a call from a number associated with one-ring scams.
Image: Current Caller ID
"We can detect suspicious patterns," Algard said. "We have a really good sense of overall network traffic, and we can detect based on the profiles of certain numbers that place phone calls in bulk."
Now, when Current Caller ID users receive a phone call from a suspicious number, the app sends a notification alerting them that the number is possibly linked to a scam or other fraudulent activity.
Current Caller ID, which first launched in 2012, offers customized caller ID that identifies incoming and outgoing calls. The app already offered spam-prevention features such as the ability to block text messages and phone calls from specific phone numbers, but Tuesday's update is the first time the app is addressing one-ring scams.
Current Caller ID is available in the Google Play Store.
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