A one-ring scam is a fraud technique where the caller rings the phone just once and hangs up, leaving a missed call entry to lure the recipient into calling back. While one-ring calls themselves serve multiple purposes including building sales lists, when used for fraud, calling back connects to premium-rate numbers that bill you international call charges, or to scam groups that extract personal information. The Japanese term "Wangiri" is internationally recognized as "Wangiri fraud."
International phone numbers (starting with +) are particularly dangerous. Country codes from Africa (Guinea +224, Sierra Leone +232, etc.) and Pacific Islands (Nauru +674, Tuvalu +688, etc.) have been reported in such calls. The scheme abuses the way revenue from an international call is shared between the originating and terminating carriers, and is known as International Revenue Share Fraud (IRSF). Criminal groups obtain numbers with high termination charges and take a share of the revenue generated each time someone calls back. Because the caller is billed at international rates, even a short call can cost an order of magnitude more than a domestic one.
Domestic one-ring scams also exist. Calling back may connect to automated messages threatening "You have unpaid fees" or "Legal action will be taken," demanding transfers to designated accounts. Other patterns involve operators who answer and extract personal information (name, address, credit card numbers). Combined with caller ID spoofing, real business or government numbers may be displayed, making it dangerous to assume safety based on the displayed number alone.
The basic defense is to never call back unknown numbers. If curious, check the caller using a phone number lookup service before deciding. International numbers starting with + should be ignored unless you have overseas contacts. Configuring your smartphone's call blocking to block international numbers in bulk is also effective. Review the latest scam patterns in one-ring scam dangers and international details in international phone scam techniques.