STIR/SHAKEN statistics from March 2023

The March 2023 STIR/SHAKEN and robocall statistics are in. These figures show welcome improvements in most areas. This article reviews the trends.

We’ve been publishing monthly STIR/SHAKEN statistics since April 2021. These numbers are gathered from over 100 voice service providers using our STIR/SHAKEN and robocall prevention solutions. The data describe calls they received from 559 other voice service providers that originated calls, including some robocalls, signed with STIR/SHAKEN.

Many Robocalls are signed with B or C attestation

Calls Signed with B Attestation Were 3 Times More Likely to be Robocalls

bar chart showing robocalls by STIR/SHAKEN verification status

Figure 1. Robocall % by Verification Status

Figure 1 compares the percentage of robocalls by attestation level, for unsigned calls, and for all calls in March 2023. Notice that calls signed with B- or C-level attestation include a high percentage of robocalls. Calls signed with B-level attestation were 3 times more likely to be robocalls than unsigned calls.

Robocalls Signed with B or C Attestation Persist

line chart comparing robocall attestations over 6 months

Figure 2. Signed Robocalls by Attestation Last 6 Months

Figure 2 shows this trend over the past six months. Notice that the red and blue lines (B and C calls) are much higher than the gray line (all calls). Fortunately, the percentage of robocalls among calls signed with C-level attestation has been on a downward trend, from 32.48% in October to 16.21% in March. Unfortunately, the percentage of robocalls among calls signed with B-level attestation has been hovering around the 20%–28% range.

SHAKEN participation is picking up

We measure STIR/SHAKEN participation changes in three ways:

  1. Originating Service Providers (OSPs) signing calls received by our customers
  2. Service providers authorized to do SHAKEN by the STI Policy Administrator (STI-PA)
  3. New certification filings in the Robocall Mitigation Database (RMD).

SHAKEN Signing Is Gaining Momentum

line chart showing the number of originating providers sending signed calls

Figure 3. Monthly Number of OSPs Sending Signed Calls

Figure 3 shows the number of Originating Service Providers (OSPs) signing calls. This had been increasing by about 10/month in previous months. However, we observed 26 new SHAKEN signers in March.

SHAKEN Authorized Providers Increasing

line chart showing an increase in SHAKEN participation

Figure 4. STIR/SHAKEN Authorized Providers by Month

Figure 4 shows the number of SHAKEN authorized providers. As with OSP signers, this number has an upward trend that has been increasing in recent months. There were 50 new SHAKEN authorized providers in March.

New Robocall Mitigation Database Filings Trickle In

bar chart showing the number of authorized SHAKEN providers by month

Figure 5. New Robocalls Mitigation Database Filings by Month

Figure 5 shows that new certification filings in the Robocall Mitigation Database are trickling in. There’s been a slight downward trend in new RMD filings, with some volatility. We expect this number to jump when the new RMD filing requirements in the Sixth Order become due.

These three measures show that the STIR/SHAKEN participation trend is picking up momentum as we approach the June 30 deadline for small facilities-based and gateway providers.

Most calls reach their destination unsigned

Most Calls Arrive Unsigned

bar chart showing the percentage of calls by verification status

Figure 6. Percentage of Calls by Verification Status

Figure 6 shows that the vast majority of calls arrive for termination unsigned.

Signed Calls at Termination Improving

line chart showing the percentage of signed calls received at termination

Figure 7. The Percentage of Signed Calls at Termination Last 6 Months

Figure 7 shows the percentage of signed calls at termination for the past six months. This figure has been hovering around 24% for a long time. In recent months, we’ve observed this number increasing by about 1% per month, reaching 28.3% in March.

Calls With Full Attestation Improving

line chart showing the percentage of calls received at termination by attestation level

Figure 8. Percentage of Calls with SHAKEN Attestation Levels Last 6 Months

Figure 8 shows that the percentage of calls signed with full attestation has been inching up slowly over the past six months, from 15.66% in October to 17.77% in March. We view this as one of the most important trends in the set, as full attestations are the most useful for robocall prevention.

woman using a laptop


Finally, we see improvement in most categories! It’s great to report some good news about call authentication and robocall mitigation.

Good news:

  • Signed robocalls with C-attestation have been trending down, even while the percentage of calls signed with C-level attestation remains level.
  • STIR/SHAKEN participation is picking up.
  • The percentage of signed calls received at termination is slowly improving.
  • The percentage of calls signed with full A-level attestation, the most useful and impactful kind, is slowly inching upward.

Remaining challenges:

  • Signed robocalls remain a problem, especially among calls signed with B-level attestation. We have found that the third-party signing loophole is a major source of this problem.
  • Although most trends are in a positive direction, we’ve got a long way to go to realize the intended benefits of call authentication and robocall mitigation.
    • Signed calls received at termination. This is being thwarted by the non-IP SHAKEN exemption. The Commission should require providers that rely on non-IP technology to either migrate to IP or implement one of the non-IP SHAKEN methods.
    • Calls received with full A-level attestation. This is undermined by the third-party signing loophole. The Commission should require voice service providers to sign calls they originate with their own SHAKEN certificate.

TransNexus solutions

TransNexus is a leader in developing innovative software to manage and protect telecommunications networks. The company has over 20 years’ experience in providing telecom software solutions including toll fraud prevention, robocall mitigation and prevention, TDoS prevention, analytics, routing, billing support, STIR/SHAKEN and SHAKEN certificate services.

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