Detect & Protect Against Wangiri Callback Fraud

Wangiri Callback Fraud is a widespread and diverse global challenge, damaging operator and service provider reputations and relationships with their subscribers.

While fraudsters are well known for their malicious innovations, they are loyal to what works; once a scamming method proves to deliver dependable results, they relentlessly take advantage over the long term. One tried and true scamming workhorse stands out from the crowd for its longevity, fraudulent profitability, and negative impact on subscribers: Wangiri, otherwise known as callback fraud, is often the revenue generating part of International Revenue Sharing Fraud (IRSF) schemes.

‘Wangiri’ loosely translates to one ring cut in Japanese. Fraudsters call a target list and avoid call completion fees by hanging up before subscribers answer. The missed call prompts some subscribers to call the number back. Subscribers’ callbacks are then re-routed to an International Premium Rate Number (IPRN) or other number charged at exorbitant fees, where they are encouraged to wait on hold. This results in significant international billable time on the line, which the fraudsters then pocket as revenue.

What can Operators do to detect and protect against Wangiri?

First detect the incoming Wangiri calls, those that entice the subscribers to call back:

  • Monitor incoming calls from high risk countries
  • Monitor large numbers of incoming very short or unanswered calls
  • Customer complaints about calls from unknown international numbers

Also monitor outgoing calls from many subscribers to international numbers with unfamiliar or high risk country codes to detect callback calls.

Take precaution and inform and warn subscribers, maintain updated blacklist(s) of known fraudulent numbers.

Most important off all is prevention. Not only maintain and share your blacklists but also block incoming and outgoing calls to/from Wangiri number ranges.

Part of our Antifraud Namespace is the capability to add/remove numbers to distributed Wangiri Blacklists. Ideally such blacklists are shared across carriers.


With the function you can add any number to the Wangiri Blacklist whereby SSIAddress is the Self-Sovereign Identity hosting the blacklist and ChainAddress and Password are required to digitally sign the addition to the blacklist.

Please note that the administrator of SSIAddress has to grant you the permission to add numbers to the blacklist.


You can use the function to remove a previously added number from the list.


The most important part is to check if a number is blacklisted. To do so you query the blacklist of the SSI for the number with the function

This function returns a long value indicating how many entities detected and blacklisted a number.


Above we explain the syntax of our web services APIs. Kindly note that we offer broad range of APIs such as websockets, RESTful APIs and of course traditional DNS AntiSPAM interfaces. Just contact us and explain how you would like to connect!