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Can We Accurately Block Robocalls?

by | Nov 12, 2021 | News | 0 comments

Written by AB Handshake

It’s time to end this nuisance for once and for all

There’s nothing more disruptive and annoying than a robocall, and no matter which anti-spam solution you choose, some robocalls always seem to get through. In fact, unwanted voice traffic is the Federal Communications Commission’s (FCC) top consumer complaint in the US.

Historically, different efforts have always been made to mitigate this problem. 

For example, the fight against robocalls recently hit a new milestone this year — July 30th was the deadline for US operators to implement the STIR/SHAKEN or an alternative robocall mitigation program. However, this protocol is no silver bullet for stopping unwanted robocalls. Something more is still needed. 

Fortunately, a new approach to fraud detection involving cross-validation of call details can put an end to this nuisance, once and for all.

No Silver Bullet

In a statement provided on June 30th, 2021, regarding the then-approaching deadline for implementing STIR/SHAKEN, FCC Acting Chairwoman Jessica Rosenworcel said:

 “While there is no silver bullet in the endless fight against scammers, STIR/SHAKEN will turbo-charge many of the tools we use in our fight against robocalls: from consumer apps and network-level blocking, to enforcement investigations and shutting down the gateways used by international robocall campaigns.

“This is a good day for American consumers who — like all of us — are sick and tired of illegal spoofed robocalls.”

Rosenworcel’s statement makes it clear that the FCC isn’t focused solely on STIR/SHAKEN — the group is encouraging service providers to use additional tools in the fight against robocalls.

Why is it that? Are there gaps in the STIR/SHAKEN protocol? Is the coverage it provides insufficient? If so, then why is it being used as the minimum standard for protection?

Stir/Shaken Matters

STIR/SHAKEN was designed to inform the end-user whether a call can be trusted and trace the source of a robocall. However, it was not designed to block robocalls. That is why service providers are now taking the next step towards using the information that STIR/SHAKEN provides and pairing it with the right tools to block all robocalls.

However, there are many questions that remain unanswered:

  • What blocking policy should service providers use? 
  • Who defines and regulates this policy? 
  • Which STIR/SHAKEN parameters can service providers use to block unwanted calls? 

At the end of the day, there really is no foolproof way to determine which calls should be blocked and which shouldn’t using STIR/SHAKEN.

With A-level attestation, we can’t guarantee that a call can be trusted — this can be undermined if a call is terminated via SIM boxes that have A-level attestation.

At the same time, a call with C-level attestation isn’t clear either — such a call could be from someone on the subscribers’ contact list. 

What’s more, even the absence of attestation isn’t conclusive — it can be lost due to a TDM segment along the path of the call.

That is why the FCC recommends employing more than one tool for the final determination. 

For example, any detection of A-number manipulation (known as CLI spoofing) can be a highly accurate indicator of a spam call and can serve as an effective way of detecting robocalls.

Innovative Alternative

Fortunately, there is an innovative alternative to fighting robocalls while meeting FCC regulations.

Unlike STIR/SHAKEN, AB Handshake’s concept of global call validation can provide a comprehensive solution to the robocall nuisance.

Rather than each company or regulator pouring resources into fraud management systems based on statistics, patterns or sampling, operators can achieve absolute protection from fraud by uniting into a single community in which all traffic shared between members undergoes cross-validation of call details.   

Such a common ‘handshake’ that cross validates the call details of both the originating and terminating call registries can detect even the slightest manipulation to a call.

Moreover, such a solution can be integrated into any company’s network using the default functionality of their existing equipment and standard protocols — no special infrastructure or hardware is needed.

It’s a simple and effective solution that is necessary for ultimately bringing an end to robocalls, once and for all.

How Cross-Validation Works

Anytime a call is made, the originating and terminating operators send verification requests directly to each other to cross-validate the parameters of the call details.

If it’s a robocall that’s using CLI spoofing to hide the true origin of the call, there will be a discrepancy in the call details between each call registry. 

In this case, the terminating operator will reach out to the owner of the A-Number used by the fraudster to no avail — they will not receive verification. 

The call is then automatically identified as fraudulent and the operator can choose to block it in real-time before it can harass customers or rack up costs for themselves or other telecom companies in the chain.

Such a ‘handshake’ can detect any type of fraud simply by identifying any manipulation to a call’s parameters in real-time. Any time manipulation is detected on a call, it can mean only one thing — fraud. Such an approach provides a foolproof logic for an automatic blocking mechanism.

Furthermore, such a solution provides value for both the originating and terminating service providers, since calls can be blocked by either operator. It provides an ultimate level of detection and control from the beginning to the end of the call chain. 

Fraud-free Community

Traffic undergoing cross-validation in this way can be used as a natural 24/7 test probe to detect any type of fraud on inbound and outbound traffic.

As more and more members join the community, the value of the network grows, and each member benefits exponentially. The volume of fraud-free traffic monitored by cross-validation grows while the amount of vulnerable traffic available to fraudsters shrinks, eventually leaving fraudsters with nowhere to go. 

If adopted on a global scale, cross-validation of call details can completely end robocalls and other fraud schemes for good. 

Final Step to Stopping Fraud

It’s reassuring to have large bodies like the FCC joining the fight against telecom fraud. Protocols like STIR/SHAKEN provide operators with useful information for detecting robocalls and other fraud schemes. Nonetheless, additional tools are necessary if we want to fully solve this issue. 

It’s an exciting time to be a part of the telecommunications industry. Not only are there other tools available to operators, but there is finally a tool that can ultimately end robocalls, once and for all.  The cross-validation of originating and terminating call details proposed by AB Handshake is an unprecedented approach to detecting and preventing telecom fraud. Moreover, this strategy allows us to achieve what, so far, hasn’t ever been possible — the complete elimination of robocalls and other telecom fraud


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