What Is a One-Ring Scam?
A one-ring scam (known as "wan-giri" in Japanese) is a fraud scheme in which scammers let a phone ring just once before hanging up, leaving a missed call in the victim's call log to lure them into calling back. When the victim returns the call, they are connected to a premium-rate number or international line, incurring exorbitant charges. According to Japan's National Consumer Affairs Center, approximately 3,000 one-ring scam complaints are filed annually, with average losses of around 50,000 yen per case. As smartphones have become ubiquitous, these scams have grown more sophisticated, targeting mobile phones as well as landlines. One-ring scam countermeasures are essential to learn in advance.
The core of a one-ring scam exploits the human habit of returning missed calls. In business settings, returning missed calls is considered basic etiquette, and scammers capitalize on this social norm. People who receive many work-related calls, job seekers, and anyone who routinely calls back unknown numbers are particularly vulnerable.
How One-Ring Scams Work
Understanding the revenue structure of one-ring scams makes it clear why this scheme persists.
Premium-Rate Number Mechanics
Scam groups use premium-rate numbers that charge far more than standard call rates. On top of normal call charges, an information service fee is added, sometimes costing several hundred to several thousand yen per minute. A portion of this fee goes directly to the scam group. When international premium-rate numbers are used, international call charges are added on top, driving losses even higher.
Automated Messages to Prolong Calls
When a victim calls back, an automated voice system plays messages designed to keep them on the line. Phrases like "We are currently experiencing high call volume - please hold" or "We are verifying your number" repeat continuously, racking up charges until the victim hangs up. Some systems use messages like "We have an important notice for you - please stay on the line" to keep victims engaged even longer.
Common Tactics
International Phone Numbers
Scammers place one-ring calls from unfamiliar international country codes. Calling back triggers international call charges of several hundred to several thousand yen per minute. Country codes from Africa (Guinea +224, Sierra Leone +232) and Pacific islands (Nauru +674, Tuvalu +688) are frequently exploited. These codes are unfamiliar to most Japanese users, who may not realize they are returning an international call.
Domestic Premium Numbers
Some scams use domestic premium-rate numbers (such as those starting with 0990, formerly used for the Dial Q2 service). Calling back triggers automated messages that prolong the call to generate charges. Although the Dial Q2 service was discontinued in 2014, similar premium-rate number services continue to be exploited.
IP Phone Numbers
One-ring calls from 050-prefix IP phone numbers are on the rise. IP phone numbers are easy to obtain, allowing scam groups to acquire disposable numbers in bulk and cycle through them rapidly. A single number may be used for thousands of one-ring calls before being discarded and replaced, making tracking extremely difficult.
Mobile Phone Numbers
One-ring calls from 080 or 090 mobile numbers have also been reported. Because these look like calls from individuals, the callback rate tends to be higher. Prepaid SIMs or fraudulently obtained SIM cards are commonly used, making identification difficult.
Damage Statistics
According to Japan's Ministry of Internal Affairs and Communications, one-ring scam losses have been trending upward again since 2020. Victims span a wide age range from their 20s to 60s, with those in their 40s and older tending to suffer higher losses - likely because the habit of returning calls is more deeply ingrained in older generations.
- Annual complaints: Approximately 3,000 (National Consumer Affairs Center)
- Average loss per case: Approximately 50,000 yen
- Most affected age group: 40s-50s
- Peak hours: Weekday business hours (9 AM - 5 PM) account for about 60%
- Callback rate: About 15% of recipients return the call
- International number usage: About 40% of cases involve international numbers
Connection to Other Scams
One-ring scams are not always standalone operations - they can also serve as entry points for other fraud schemes.
- Harvesting active numbers: Numbers that call back are flagged as "live" and added to target lists for future scams such as investment fraud or fake billing schemes
- Confirming occupancy: Returning a one-ring call can reveal whether someone is home, potentially making them a target for burglary or in-person scams
- Phishing redirection: Some automated callback messages direct victims to fake websites with instructions like "Visit our website for details," where personal information is harvested
How to Protect Yourself
- Never call back unknown numbers: Be especially cautious with unfamiliar area codes or country codes. Ignoring unexpected calls is the safest approach. If the call is important, the caller will leave a voicemail or call again.
- Look up the number first: Search the number on this site to check for user reports. Google searches can also reveal whether a number has been flagged as suspicious.
- Block repeat offenders: If the same number calls repeatedly, add it to your block list using your phone's built-in features or your carrier's nuisance call service.
- Use carrier protection services: NTT Docomo's "Anshin Security," au's "Nuisance Call Blocker," and SoftBank's "Nuisance Call Block" automatically filter known scam numbers for a small monthly fee.
- Restrict international calls: If you don't need to make international calls, contact your carrier to disable outgoing international calls. NTT's International Call Restriction Center (0120-210-364) can block international dialing from landlines.
- Install a call-screening app: Apps like Whoscall and Phone Number Navi display caller information in real time using global databases of reported numbers. Nuisance call countermeasures are also worth considering.
What to Do If You've Been Scammed
If you've incurred unexpected charges, follow these steps. First, save your call records as evidence. Then contact the Consumer Affairs Hotline (dial 188) for expert advice. For serious cases, consider calling the police consultation line (#9110). You may not be legally obligated to pay fraudulent charges, so consult a professional before making any payments.
Step-by-Step Response
- Check and save your call records: Review your carrier's app or website for suspicious calls, noting the date, number, duration, and charges
- Contact your carrier: Report the fraudulent charges. For international calls, some carriers may reduce or waive the fees
- Call the Consumer Affairs Hotline: Dial 188 to reach your nearest consumer affairs center, where specialists can assist and negotiate with service providers on your behalf
- Set up international call restrictions: Prevent future incidents by blocking outgoing international calls
Where to Get Help
- Consumer Affairs Hotline: 188
- Police Consultation Line: #9110
- Ministry of Internal Affairs - Telecom Consumer Consultation Center: 03-5253-5900
- International Call Restriction Center: 0120-210-364
- Your carrier's customer support
For related protection measures, see also How to Block Nuisance Calls, Dealing with International Spam Calls, and Caller ID Spoofing Risks.
Smartphone Prevention Settings
Smartphones offer several built-in features to help prevent one-ring scams. Use these settings to minimize your risk.
iPhone Settings
- Silence Unknown Callers: Go to Settings > Phone > Silence Unknown Callers. Calls from numbers not in your contacts will be silenced and sent to voicemail, though they will still appear in your call history
- Block a number: Tap the number in your call history and select "Block this Caller." Manage blocked numbers in Settings > Phone > Blocked Contacts
Android Settings
- Spam call filtering: Enable spam filtering in your Phone app settings to receive warnings about suspicious incoming calls
- Block a number: Long-press the number in your call history and select "Block number." Google's Phone app also offers automatic spam detection
- Caller ID for unknown numbers: Google's Phone app can automatically display information about unknown callers by cross-referencing its database