Why the battle against spam is still ongoing

What are the challenges to winning the war on phone spam? 

That’s the question Hiya’s Director of Product Management Jonathan Nelson addressed at last week’s State of the Call Summit in New York City. The summit, hosted by Hiya, featured 30 guest speakers and gathered together the brightest minds in the industry to discuss how they can collectively restore trust in the voice call and improve the consumer experience.

Hiya’s Director of Product Management Jonathan Nelson at Hiya’s State of the Call Summit in New York City.

According to Nelson, one reason phone spam is still a problem is because while STIR/SHAKEN has been helpful in identifying unwanted calls in mobile traffic, it has been less helpful in identifying unwanted calls coming from non-mobile lines. And that’s important because most unwanted calls come through non-mobile lines.

What is STIR/SHAKEN?    

STIR/SHAKEN is a framework designed by the telephony industry to meet FCC goals to verify the digital signature of a call and prevent spoofing. 

STIR/SHAKEN requires carriers to assign an attestation level to each incoming call. “A” level (fully signed) means the carrier has verified the caller’s identity and is authorized to use the phone number. “B” indicates the carrier can identify the caller's location but can’t verify if the user is authorized to use the phone number. “C” is given when the carrier can ascertain where the call was received but not the call’s origination. 

June 30, 2023 marked the deadline for nearly all types of carriers (large, small, gateway providers) to implement STIR/SHAKEN.

STIR/SHAKEN is valuable for mobile calls

For mobile calls, currently, 89% of calls are fully signed, meaning they carry an “A” attestation. And the likelihood of an A-level call being spam is relatively low. However, a mobile call with a “B” or “C” attestation is more than 100 times more likely to be unwanted. 

“It’s difficult for a mobile phone call to receive anything other than A-level attestation,” says Jonathan Nelson, Director of Product Management at Hiya. “On the other hand, it’s nearly impossible for spoofed calls to get A-level attestation. That separation means our challenge to detect malicious spoofing has gotten much easier, thanks to STIR/SHAKEN.”

Less effective for identifying unwanted calls on non-mobile lines 

STIR/SHAKEN has been less helpful in identifying unwanted calls in the non-mobile space. To start, only 34% of non-mobile calls carry the “A” attestation (fully signed), while 23% have “B” or “C” attestation, and 56% are unsigned.

But even when a non-mobile call is fully signed, there’s still a good chance it is an unwanted call. In fact, more than one in five unwanted calls will be fully signed at the A level in the non-mobile space. 

That’s not too surprising, given the objective of STIR/SHAKEN. “Unlike the mobile call space, there are many reasons that a non-mobile call wouldn’t have A-level attestation,” says Nelson. “Plus, there’s no reason to believe those that do have A-level attestation are going to be wanted phone calls. All STIR/SHAKEN says is that the call isn’t spoofed. That doesn’t mean the call isn’t spam.”   

21% of A-level calls on non-mobile lines are unwanted despite having the highest STIR/SHAKEN attestation. 

Despite its limitations, STIR/SHAKEN has benefitted enforcement efforts, making finding and stopping scammers faster.  

According to Nelson, even though the FCC deadline has passed, many carriers are still working through their policies on applying STIR/SHAKEN, so further changes are expected. “Hiya will be watching developments to see how the spam ecosystem changes in the new world of widespread STIR/SHAKEN adoption,” Nelson said.

Learn more

To discover the latest data on phone spam in the US, Canada, and the UK, download the State of the Call Summit 2023 Report below.