May 4, 2022

Are Attestation Ratings Accurate Across Carriers?

Attestation ratings are one of the major factors in STIR/SHAKEN call authentication, and yet this process is still lacking in consistency and fairness. The goal of attestation is to determine the legitimacy of a call's origin. When attestation works, it allows carriers to determine the risk associated with the call. Carriers can better decide if the phone number has been spoofed to deceive call recipients.

Are Attestation Ratings Accurate Across Carriers?

However, one problem with STIR/SHAKEN is the timing. These regulations were scheduled to be implemented by June of 2021, but many carriers are falling behind. They have yet to fully implement attestation, which is a problem for call centers and consumers both.  

Delay in STIR/SHAKEN Implementation

This delay in implementing attestation ratings threatens the success of the entire effort to control robocall, spam calls, and scam calls. STIR/SHAKEN simply will not work as it was intended if this problem is not corrected. The government gave smaller voice service providers extensions to “catch up” with attestations requirements, but the industry will continue to struggle until the issue is completely resolved. A recent case study emphasizes the severity of the problem.

Case Study on Attestation Rating Implementation

Next Caller (using VeriCall Technology) began a case study on attestation rating analytics prior to the full implementation of STIR/SHAKEN in June 2021. The study analyzed traffic in over 500 networks, including major carriers. It found that implementation of attestation ratings rose after STIR/SHAKEN, but the numbers appeared to have plateaued, leaving many calls without any assigned attestation ratings.

To make matters worse, the attestation ratings assigned by carriers were often inaccurate. So, the key foundation of STIR/SHAKEN is not working as it should, which certainly harms the industry.

Attestation Ratings Not Available

The Next Caller's survey of network traffic also showed that prior to June of 2021 (in April and March), less than 30% of calls analyzed had attestation ratings when delivered to the call recipient. In June, that number increased to 36%. However, in the months following, this number appeared to have plateaued, an unexpected and troublesome finding. Progress in attestation quickly stalled.

On the other hand, many calls were scored "Green" (in VeriCall's scoring system) yet failed to have attestation ratings attached. A "Green" score in the VeriCall scoring system is equivalent to Attestation A. Correspondingly, a "Red" score corresponds to Attestation C.

In effect, many calls were awarded Attestaton A ratings, without appearing to meet the requirements.

Attestation Ratings Inaccurate

Of the calls that did relay attestation ratings in the SIP headers, some of these were inaccurate. The study showed that approximately 117,000 calls with Attestation A still posed a spoofing risk. In these cases, the device originating the call may not have owned the numbers. These calls scored a "Red" score with VeriCall's technology.

In some of these cases, spoofed calls actually received Attestation A ratings. These ratings are meant to give consumers confidence that they are not answering a spoofed call. When they answer and find a spammer or scammer, their trust is further compromised. 

While analyzing Attestation C calls, a similar pattern was noticed. Almost 300,000 calls relayed an Attestation C rating in the SIP header but were scored "Green" through VeriCall's technology. This mislabeling leads to a disconnect between call authentication methods.

In short, “good” calls are being ranked as problematic while “bad” calls are getting good marks. It’s confusing for consumers and harmful to legitimate outgoing call campaigns. 

The PSTN Factor

STIR/SHAKEN regulations only work on VoIP networks. While these networks make up the majority of call traffic, the Public Switched Telephone Network (PSTN) is still considered "neutral ground.” Some VoIP infrastructures are incompatible with each other, leaving the PSTN as a medium between networks. Although the traditional copper-wire system is being overshadowed by new technologies, it is still necessary to complete many VoIP calls.  

Many VoIP Calls Still Rely on PSTN

While the future of voice communications is in VoIP, the infrastructure hasn't caught up yet. Since some VoIP calls are routed through PSTN networks, this means that SIP headers may get lost in this communication. This makes attestation near impossible calls routing through the PSTN. Without these call identifiers, STIR/SHAKEN’s intent is thwarted.

To further complicate things, blocking calls with no attestation rating is simply not possible at this time. Doing so would result in all calls that go through a PSTN network being blocked, meaning consumers would be missing many legitimate calls.

The PSTN system will remain a factor for some time to come, so attestation ratings need to be analyzed in different ways to ensure legitimate calls still reach their destinations. 

Attestation Issues and Service Providers

Since the technology is still new, there is a disconnect between service providers and enterprises in issuing attestation ratings. Many service providers do not meet the Governance Authority's (GA) criteria to obtain a certificate. Since they do not have the proper certification, they cannot sign their own calls and must rely on the Operating Service Providers (OSPs) to do this.

Enterprises often look for the most cost-effective phone numbers to lower their overhead expenses. However, buying blocks of bulk numbers means that many of these purchased numbers end up routed through multiple Operating Service Providers (OSPs). In addition, some of these employ Least Call Routing (LCR) to lower costs on connecting calls.

Using these methods can cause you serious problems. Calls from the same enterprise can appear differently on the consumer's phone. One call may receive an Attestation A rating while a call going through another OSP receives an Attestation B or C rating. These discrepancies make it difficult to pinpoint specific problems and create a standard for handling these calls.

Attestation Awareness is Important

Call attestation is at the heart of STIR/SHAKEN framework, but it still has many implementation issues. While service providers hammer out the best ways to implement the process seamlessly, some businesses will get caught in the cracks. These problems are costly for your business and increase consumer distrust of outbound calling campaigns. 

Even with problems such as poor attestation accuracy, you still have to maintain attestation awareness. Although an attestation rating may not be completely accurate, it is important to monitor your calls’ attestation ratings. Doing so can help pinpoint possible issues with your numbers or the service providers in your calling architecture.

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