Wangiri Fraud - Alert to callers and international businesses of wealthy countries

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how to stop wangiri calls scam ab handshake
If you're a resident of the USA or Canada, you may be familiar with Wangiri scams. You receive a missed call from an unknown number that rings once and stops. So you call back only to reach an audio recording and hang up. You've just been a victim of a Wangiri scam. While it seems insignificant, the charge for this call on your phone bill turns out to be enormous.

This dubious fraud scheme, called 'Wangiri Fraud', does enormous damage to end-users and businesses alike. It steals billions of dollars from end-users each year, destroys customer relations, overloads operator circuits and inflicts irreparable churn upon businesses.

The damage from Wangiri fraud around the world in US dollars is staggering. Added together, the total global telecom revenue loss from fraud was estimated at $39.8 billion in 2021. Wangiri calls, alone, were responsible for $2.23 billion of that, with the wealthier countries of the world, like the USA and Canada, bearing the majority of these losses.

While traditional fraud management systems (FMS) in these nations utilize ultra-modern, well-intended technology like machine learning and artificial intelligence, they have struggled to stop all Wangiri calls.

So, do we have to simply accept these losses, like a tax, and carry on?

Fortunately, we don't. With new fraud prevention technology based on the cross-validation of call details, we can stop this harmful fraud scheme, once and for all.

Wangiri Fraud - Regional face of fraud

This is the third article in our 'Regional Fraud' series. By the end of this article, you will know:

  • What Wangiri fraud is and how it works
  • Why it's rampant in wealthy countries like the USA, Canada, Europe and the Middle East
  • Why a traditional FMS struggles to detect and stop Wangiri attacks
  • How we can eliminate Wangiri callback fraud, for good
Let's waste no more time, and dive right in.

What is Wangiri Fraud?

What are Wangiri calls? To better understand this issue, we need to first answer the question, 'What is Wangiri fraud?'. Here's a definition:
Wangiri callback fraud is a form of International Revenue Share Fraud (IRSF) in which fraudsters earn a profit by artificially increasing traffic to international premium-rate numbers (IPRNs) or expensive destinations. They do this by making one-ring calls to subscribers' phones to entice them into calling back and racking up exorbitant charges.
There are few costs to the fraudsters who initiate the one-ring scam calls - the majority of these calls are disconnected before the targeted subscriber answers.

And while only a small percentage of these one-ring phone scams successfully trigger callbacks, each attack can generate hundreds of thousands of 'missed calls' in one day to customers of one or more mobile operators. Even a small percentage of callbacks generates enormous profits.

So, how does Wangiri work?

Two 'Legs' of Wangiri Fraud

Wangiri consists of two 'legs'. The first leg of this one-ring phone scam involves generating the 'missed calls'. The second involves the 'callbacks'.

Different variations in each leg and their inherent nature make it difficult for traditional fraud management systems to detect and block it.

To better understand why this is so, we need to understand the three tactics Wangiri scammers use.

3 Wangiri Fraud Tactics

Here are the three tactics Wangiri fraud utilizes.

1. Corrupt Owner of a Premium Rate Number

The owner of a so-called IPRN generates one-ring scam calls from their number capacity to hundreds of thousands of subscribers from one or more mobile operators.

Some subscribers call back to this premium rate number and reach an audio recording, automated menu or other distraction intended on keeping them connected for as long as possible while racking up charges. The caller lingers for several moments before hanging up.

Here, the fraud takes place on the first leg. This is incredibly difficult to track as there is no chargeable duration. Also, the terminating operator has no way of knowing whether the number is high or low risk, and can't confidently decide whether or not they should block it.

In the second leg, users call this number back only to reach a premium rate number with a mysterious recording.

The wholesale carrier transiting this call back to the fraudulent number range may block it if they detect a suspicious pattern. But, carriers will often just overflow the calls to another wholesale operator to ensure the calls connect.

In the end, the corrupt owner of this range successfully generates an artificial boost in traffic to their service, increasing their revenue.

2. Fraudulent Carriers Cooperate to Reroute Calls

A corrupt transit operator colludes with a fraudster to commit one-ring scams.

The fraudster generates 'missed calls' with the A-number of an expensive destination or an IPRN. The corrupt transit operator hijacks the callback traffic and routes it to a fraudulent terminating operator who may even connect this traffic to real people from a call center, all with the same intention - to keep the callers connected as long as possible and rack up charges.

The fraudsters then split the profits.

Here, the fraud takes place on the second leg, where the callback occurs and where the corrupt transit and terminating operators work.

In today's telecommunications landscape, a traditional FMS on an operator's network operates in isolation from other networks, with essentially no communication between one another. This makes it difficult to determine that a call has been hijacked at any point in the call chain.

Herein lies both the problem, as well as the solution, for stopping Wangiri callback fraud, for good. One single operator will never overcome Wangiri fraud by itself. Detecting it with 100% accuracy requires communication between operators. We'll discuss this in detail later on in this article.

Before we do that, let's look at the third tactic Wangiri fraudsters use for call-back scams. It's relatively young and targets enterprises, instead of end-users.

3. "Wangiri 2.0"

Within the past several years, a new type of an unknown caller scam very similar to Wangiri was discovered. What distinguishes this scheme from traditional Wangiri fraud is the party it targets: instead of telcos and their customers getting outplayed, the real victims here are enterprises, whose call centers are duped into calling back high-rate numbers.

This new type of fraud was appropriately named "Wangiri 2.0".

In a Wangiri 2.0 attack, bots generate callbacks by submitting phone numbers into hundreds of thousands of online business contact request forms. The callback traffic (made by the business' call centers) is then routed via the same tactics used in the above two schemes.

Businesses can easily mistake this traffic as a natural boost in contact requests, while they are in fact being duped into wasting their marketing budget.

These are the three main schemes Wangiri scammers use. Now, who is the first to suffer from these attacks? Subscribers in wealthy nations.

Global Losses Due to Wangiri Scams - Who's hurt most?

Customers in wealthy regions such as North America, Europe and the Middle East are the first to suffer from Wangiri scams.

Users in the United States and Canada are particularly affected. Fraudsters often take advantage of the North American Numbering Plan (NANP) to more effectively dupe customers in these countries into calling back.

Wangiri scammers often attack customers in the USA and Canada with NANP A-numbers that belong to Caribbean countries. In this case, the victim calls back, thinking that the call came from the USA and will actually be free (included in their cellular plan). Instead, they pay for an international call.

Naturally, experts in the field have developed solutions to mitigate these attacks. While the current solutions can stop some callback scams, they struggle to effectively and accurately block them all.

While missed call scams are quite common for North America and Europe, 2020-2021 revealed a rapid increase in Wangiri scams in the Middle East.

Let's have a look at this issue, in detail.

Shortcomings of Traditional Anti Fraud Systems

Today, Wangiri scams remain of the most dangerous fraud schemes around and stand as one of the most challenging for traditional fraud solutions to detect and stop.

Operators have established black lists in an attempt to stop one-ring scams. They try to maintain the base of the given IPRN numbers and other ranges used by this scheme, and attempt to stop incoming one-ring calls from these numbers as well as outgoing calls to them. However, the fraudsters regularly acquire new number ranges and the databases quickly become outdated.

Most experts have turned their focus to AI-based fraud management systems and train them to better detect Wangiri patterns.

However, there are two key issues here:

  • The fragmented nature of the global telecommunications service
  • The isolated and reactive approach operators use to protect their networks
These two issues leave major opportunities for Wangiri scammers to pump out missed calls from unknown numbers, abuse the callbacks and steal billions of dollars each year.

Let's explore these, in detail.


Telecommunications is fragmented, by nature. This leaves many opportunities for fraudsters to embed themselves in the call chain at many points along the call. This also has implications for how we can most effectively stop telecom fraud. Much like we would attempt to stop a viral pandemic, we need a fraud vaccine.

For example, many of the callbacks in a Wangiri scam are delivered via multiple network operators. A single voice call can originate on one cellular network and terminate on another fixed-line network, which involves a separate provider.

A more intricate session is just as common. For example, a call may begin from a cell phone outside of the USA, then transit the globe via one long-distance network or via several networks provided by other telecom operators before terminating on yet another mobile network, within the USA.

Each piece of the call chain can serve as an 'entry point' for the fraudsters.

The next piece of this problem is the isolation in which operators work.

Isolation and Reactive Approach

The traditional approach to preventing call-back phone scams and other fraud schemes has always been inward-focused and reactive.

Experts have developed advanced fraud management systems for mitigating Wangiri scams based on digital signatures, in-band SIP signaling, artificial intelligence and other ultra-modern, well-intended technologies.

The goal here is to operate as a 'wall of defense', so to speak, around their networks. However, they ignore what's happening along other segments of the call chain, which is costly.

Without a way to communicate with other operators in real-time and see what's happening at other points in the call chain, abuses go undetected. Operators successfully detect and stop only some attacks. Moreover, their approach is reactive. They respond to attacks only after they occur and adjust their protocols accordingly in hopes of preventing similar future attacks.

All of these issues, combined, have resulted in an ongoing game of cat-and-mouse between fraudsters and operators. The fraudsters remain steps ahead of the operators, maintaining a foothold in the market and successfully stealing billions of dollars from end-users each year.

Here's what these losses amount to, in USD.

Global Loss to Wangiri Fraud in USD

According to the CFCA global fraud loss surveys:

While our goal is to ultimately eliminate fraud for good, statistics from the past several years indicate that Wangiri is on the rise.

Additionally, as revenue losses to telecom fraud have continuously risen, this effect has been slightly amplified amid the COVID-19 pandemic.

The problem goes beyond financial loss. Missed call scams also amount to reputational and logistical damages.

Additional Costs of Wangiri Fraud

The damages from Wangiri aren't only a matter of financial loss. This scheme also inflicts devastating reputational losses for carriers and creates crippling logistical problems.

Financial and Reputational Loss

Firstly, hundreds of thousands of users in North America, Europe and the Middle East face enormous phone bills from each successful attack, which they then often dispute with their mobile carrier.

The victims have simply called legal numbers or, in other cases, a corrupt transit carrier 'invisibly' hijacked their call. This makes it almost impossible for mobile carriers to effectively resolve the disputes. The carriers are met with a dilemma — either refund the costs or risk churn.

Additionally, carriers can't detect a suspicious call with 100% certainty. Therefore, they face another dilemma – they must choose between allowing an outgoing international call (and, accordingly, to profit from it) or to deny it and risk negative customer experiences.

Many in this industry ask,

What can operators do to better protect themselves and their customers?

Do these countries simply have to accept these losses, like a tax?

Despite the sophisticated tactics Wangiri scammers use to successfully avoid detection, all calls made across any network at any time have one thing in common - call details. It is with these call details that we can detect and stop 100% of all Wangiri scams with absolute confidence and zero false negatives.

Let's explain.

Cross-validation - How to stop Wangiri calls

To understand how to stop one-ring calls, we must first look at the fragmentation problem mentioned above.

Solving the fragmentation problem requires industry collaboration. This can be achieved by allowing operators to communicate and cross-validate call details in real-time as they are being set up.

With such a solution, operators can effectively detect even the slightest manipulation at any point on the call chain with 100% accuracy and stop a one-ring scam before it connects.

This is the principle on which the AB Handshake solution operates.

While the technology is revolutionary, the end product is simple, lean and effective. It's also available for any operator in any country around the world.

AB Handshake - How to stop Wangiri calls, for good

AB Handshake is a solution that operates on the principle of cross-validating the call details from the A and B call registries of a call. It's a guaranteed method for stopping call-back scams.

Here's how it works:

  1. As soon as a call is initiated, the originating network records key call details to Call Registry A. Details include the A and B numbers as well as a time-stamp for the start of the call.
  2. The terminating network then sends their respective call details to Call Registry B.
  3. Both registries simultaneously exchange encrypted messaging via the internet to cross-validate these call details.
Any discrepancy between the call details indicates one thing - fraud. Such a call is immediately flagged as fraud and blocked before it connects.

In the case of one-ring scams, when fraudsters spoof the CLI or partner with fraudulent carriers to hijack a call, a discrepancy will appear between the A and B call registries. Any such call will be blocked.

With AB Handshake, operators in hard-hit regions like the USA, Canada, Europe and the Middle East can shift from a reactive game of cat-and-mouse to proactively eliminating Wangiri fraud before it strikes.

Fraud Free Community - How to stop Wangiri calls

All operator traffic monitored by the AB Handshake solution is guaranteed to be free from Wangiri and all other forms of voice fraud with 100% accuracy and zero false positives.

As more operators adopt the AB Handshake solution, the community expands. The portion of fraud-free traffic grows while the share of fraudulent traffic shrinks, eventually leaving the fraudsters with nowhere to go.

If adopted on a global level, AB Handshake can eliminate all Wangiri attacks for good.

In order to make such a vision a reality, the team behind AB Handshake understood that affordability and adoption were key. Any solution had to be both affordable and compatible with the default settings of any operator's current network and FMS.

Seamless, Affordable Integration

AB Handshake is a light, easily integrated, low-cost solution that can be adopted by any operator around the globe. Counter to the signature-driven, in-band, SIP signaling technology used in most traditional fraud management systems, AB Handshake's lean, out-of-band foundation is key to its success.

Traditionally, the integration stage of an FMS takes a lot of time and effort, which results in greater costs. Integrating AB Handshake can take as little as one week. Short implementation time allows us to reduce integration costs.

Onboarding is a simple process. Specialists assist in installing the AB Handshake software onto a dedicated server. They then configure it with your current network equipment and the system is ready to use.

You have the ability to customize your personal security policy rules for in- and outbound voice traffic. Once active, you can monitor the whole validation process via an online interface that offers transparency and allows you to see all activity on the system.

Partner With AB Handshake Today

Operators in the USA, Canada, Europe and the Middle East can finally protect their businesses and their subscribers from Wangiri scams. Businesses are beginning to feel relief from the relentless financial, reputational and logistical burdens of these one-ring phone scams.

The AB Handshake community is currently working with 200+ operators at various integration stages, including negotiation, contract signing and onboarding.

We are actively onboarding providers from any location around the world and the solution is already validating live traffic in every country in the world.

If you're interested in joining the AB Handshake community, or you just have some questions, feel free to contact us here. One of our onboarding specialists will respond today.