STIR/SHAKEN statistics from April 2024

The April 2024 STIR/SHAKEN and robocall statistics are now available. The data show the latest trends in robocalls, STIR/SHAKEN participation, and attestation level usage.

We’ve been publishing monthly STIR/SHAKEN statistics since April 2021. These numbers are gathered from well over a hundred voice service providers using our STIR/SHAKEN and robocall prevention solutions. The data describe calls they received from 980 other voice service providers that originated calls, including some robocalls, signed with STIR/SHAKEN.

Many robocalls are signed with B or C attestation

Robocalls down slightly

Line chart comparing robocall attestations over 6 months

Figure 1. Signed Robocalls by Attestation Last 6 Months

Figure 1 shows robocalls by attestation level over the past six months. The numbers are encouraging. Robocalls were down 0.4% for calls signed with A-level attestation, down 2% for calls signed with B-level attestation, and down 2.7% for calls signed with C-level attestation. Overall, robocalls were down 0.45%.

STIR/SHAKEN participation and coverage

We measure STIR/SHAKEN participation changes in two ways:

  1. The number of Originating Service Providers (OSPs) signing calls received by our customers,
  2. Service providers authorized to do SHAKEN by the STI Policy Administrator (STI-PA),

SHAKEN signing up slightly

line chart showing the number of originating providers sending signed calls

Figure 2. Monthly Number of OSPs Sending Signed Calls

Figure 2 shows the number of Originating Service Providers (OSPs) signing calls. We saw 18 new SHAKEN signers in April, a 1.9% increase.

The number of SHAKEN-authorized providers up slightly

line chart showing an increase in SHAKEN participation

Figure 3. STIR/SHAKEN Authorized Providers by Month

Figure 3 shows the number of SHAKEN authorized providers. There were 21 additional SHAKEN-authorized providers in April, a 1.6% increase.

These two measures show that the STIR/SHAKEN participation increased slightly.

STIR/SHAKEN coverage

Signed calls at termination up slightly

line chart showing the percentage of signed calls received at termination

Figure 4. The Percentage of Signed Calls at Termination Last 6 Months

Figure 4 shows the percentage of signed calls at termination for the past six months. This statistic was 338.9% in April, up from 34.0% in March.

It’s good news to see increases in participation and signed calls at termination. However, this level of coverage is still too low for the effective use of call attestation information by terminating providers. The primary reason for low STIR/SHAKEN coverage is widespread non-IP interconnections across the telephone network.

Calls with full attestation increase

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

Figure 5. Percentage of Calls with SHAKEN Attestation Levels Last 6 Months

Figure 5 shows the percentage of calls signed by attestation level. Calls signed with full A-level attestation were 28.0% in April, up from 26.5% in March. Legitimate A-level attestation is a good thing when the authenticating provider knows the caller and can attest to their valid use of the calling number. However, we continue to see evidence that some authenticating providers are providing illegitimate A-level attestations.

financial graph

Patterns among prolific robocall signers

Here are robocall and attestation statistics for the top 10 SHAKEN-authorized providers ranked by the percentages of signed calls identified as robocalls.

Robocalls with A- and B-level attestation from prolific robocall signers down

robocalls among calls with A-level attestation are increasing

Figure 6. Robocall Percentage by Attestation—Prolific Robocall Signers by Robocall %

Figure 6 shows robocalls authenticated by prolific robocall signers over the past six months. In April, these robocall percentages were down 2.0% for calls signed with A-level attestation, down 10.6% for calls signed with B-level attestation, and up 3.5% for calls signed with C-level attestation.

It’s encouraging to see some improvement with calls signed with A- and B-level attestation. We believe that terminating providers should evaluate the reputation of STIR/SHAKEN signers and use it as input to call validation treatment.


  • Overall robocalls were down.
  • STIR/SHAKEN participation increased slightly.
  • STIR/SHAKEN coverage improved.
  • The percentages of robocalls signed by the top 10 prolific robocall signers were down for A-and B-level calls, and up for C-level calls.

TransNexus solutions

TransNexus is a leader in developing innovative software to manage and protect telecommunications networks. The company has over 25 years of experience in providing telecom software solutions including branded calling, toll fraud prevention, robocall mitigation and prevention, TDoS prevention, analytics, routing, billing support, STIR/SHAKEN, and SHAKEN certificate services.

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