Wangiri fraud ("one ring and cut" in Japanese) is a scam where people receive a missed call from an international number, usually after a single ring, so that they call back a high cost number whose revenue the fraudster shares. Carriers stop it by spotting bursts of very short unanswered calls and blocking callbacks to the abused ranges; people avoid it by not returning unknown international missed calls.
How Wangiri works, in short
Fraudsters place large numbers of very short calls to mobile subscribers, timed to hang up before the call can be answered. The caller ID shows an international number in a range that pays high termination rates. Some recipients call back out of curiosity and are charged international or premium rates, sometimes kept on the line with a recording. The revenue from the callbacks is shared along the termination chain, which makes Wangiri a feeder for international revenue share fraud.
A variant, sometimes called Wangiri 2.0, uses web forms, voicemails or text messages instead of missed calls to make people call or request a call to a high cost number. The defence is similar.
Signs a network sees
| Pattern | Why it matters |
|---|---|
| Bursts of inbound international calls released after 1 to 2 seconds of ringing | The calling stage of the attack |
| Many calls from sequential or similar caller IDs | Numbers from the same rented range |
| Calls sweeping through consecutive subscriber numbers | The attacker dials blocks of numbers, not real contacts |
| Sudden outbound calls from many subscribers to the same unusual range | The callback stage, which is where the money is |
| Inbound traffic with very high attempts and almost no answered minutes | Visible in route statistics as near zero ASR and SDC peaks |
The same CDR analysis used for route quality catches these patterns, see monitoring route quality with CDRs and short duration calls.
What carriers can do
- Detect the inbound burst: rules that flag high volumes of short, unanswered international calls from one range or one interconnect partner.
- Protect the callback: once a range is identified, block or warn on outbound calls to it, or play a cost announcement before connecting.
- Check caller ID validity: calls with caller IDs that are malformed or from ranges not in service can be screened. See CLI spoofing and robocall rules.
- Share intelligence: Wangiri ranges change quickly; operators and fraud groups exchange lists of abused numbers.
- Hold upstream: refuse to accept transit traffic that matches the pattern, and agree in your contracts that payment for confirmed fraudulent callback traffic can be withheld. See the interconnect agreement checklist.
What businesses and users can do
- Do not return missed calls from unknown international numbers. Real callers leave a message or call again.
- Look up the country code before calling back.
- For company phones, bar outbound calls to destinations the business does not need, or require a PIN for them. The same controls help against toll fraud.
- Report suspicious missed calls to your operator.
Why it matters for wholesale buyers
If you resell voice, your customers' callbacks to Wangiri ranges go through your routes and appear on your invoice. Spend alerts per destination, sensible destination limits per customer and fast blocking keep the cost small. When you request routes, ask only for the destinations your traffic needs.
VoIPMatcher sources VoIP termination for the destinations you specify and manages the route with the supplier. Request a VoIP route.
Frequently asked questions
What happens if I call back a Wangiri number?
You are usually connected to a premium or high cost international number and charged per minute, sometimes kept on the line with music or a recording. The cost appears on your phone bill. If you called back by mistake, hang up, check your bill and report the number to your operator, which may block the range.
Is Wangiri a scam?
Yes. Wangiri is a scam that relies on curiosity: a missed call from an unknown international number prompts a callback to a high cost number whose revenue is shared with the fraudster. Receiving the missed call costs you nothing; calling back is what costs money, so the simplest protection is not to return such calls.
Which country codes are used for Wangiri calls?
They change constantly. Fraudsters rent ranges in destinations with high termination rates, often small or remote countries and satellite or premium services, then move on once operators block them. Rather than memorising codes, treat any unexpected missed call from an unfamiliar international code with suspicion and look up the code before calling back.
Can a Wangiri call hack my phone?
No. A missed call cannot install anything or take data from your phone. The only cost comes from calling the number back, which is billed at international or premium rates. Some variants use texts or voicemails asking you to call back, so the same rule applies: do not return unknown international calls.
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