STIR/SHAKEN statistics from May 2024

The May 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 981 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

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 0.2% for calls signed with A-level attestation, down 4.4% for calls signed with B-level attestation, and down 2.8% for calls signed with C-level attestation. Overall, robocalls were down 0.6%. These decreases are like what we observed in April 2024.

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 level

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 a net increase of 1 additional SHAKEN signer in May.

The number of SHAKEN-authorized providers level

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. We saw a net increase of only 2 additional SHAKEN-authorized providers in May.

These two measures show that the STIR/SHAKEN participation remained level.

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 39.1% in May, up slightly from 38.9% in April.

STIR/SHAKEN coverage seems to be settling in at a level that is far too low to realize the benefits of call authentication. This is because of the widespread use of non-IP interconnections across the telephone network. Coverage can only be extended in a meaningful way by interconnection carriers replacing non-IP connections with SIP connectivity or by a mandate for them to use an approved method for transmitting SHAKEN information across non-IP barriers, such as Out-of-Band SHAKEN, for example.

Calls with full attestation level

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 28.3% in May, up slightly from 28.0% in April.

blue three-dimensional graph

Patterns among prolific robocall signers

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

Robocalls 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 May, these robocall percentages were down 3.7% for calls signed with A-level attestation, down 12.9% for calls signed with B-level attestation, and down 5.9% for calls signed with C-level attestation. The robocall percentage for all calls among the most prolific robocall signers was down 8.0%.


  • Overall robocalls were down slightly.
    • Robocalls were down 4.4% among calls signed with B-level attestation.
  • STIR/SHAKEN participation increased slightly, but was essentially level.
  • STIR/SHAKEN coverage improved.
  • The percentages of robocalls signed by the top 10 prolific robocall signers were lower across all attestation levels.

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.

Contact us today to learn more.

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