Reply comments on SHAKEN extensions and effectiveness

The FCC received reply comments on whether STIR/SHAKEN extensions are needed and if STIR/SHAKEN effectiveness. Here’s a summary.

Recurring themes

  • Several commenters wrote that SHAKEN efficacy is limited by improper attestation levels, such as signing calls with full A attestation that don’t deserve it.
    • The most pointed example was calls with full A-level attestation and invalid calling numbers. (It isn’t clear how much of this stems from malicious intent versus configuration errors.)
  • Several commented that the lack of an all-IP network is limiting SHAKEN effectiveness.
  • Some commenters stressed the importance of having calls signed by originating providers that actually know the callers and calling numbers. There were similar suggestions in the first round of comments.


There were 32 pages of comments from six organizations. Here are summaries of each. You can click the filer’s name above each summary to read that organization’s filing.


  • For consumers to reap the full benefits of STIR/SHAKEN, all entities in the ecosystem must conform to the STIR/SHAKEN standards.
  • CTIA’s largest members say that nearly 70% of the calls entering their networks are signed.
    • TransNexus reports that only 15-24% of calls are signed. This may be because traffic passes through intermediate TDM switches and non-IP interconnects.
  • The Commission should encourage providers to sign calls in a consistent and disciplined manner.
    • Some providers are assigning a higher level of trust than is warranted. This undermines STIR/SHAKEN and the additional tools that rely on accurate SHAKEN data.

HD Carrier

  • HD Carrier welcomes an all-IP reciprocal bill-and-keep arrangement.
  • The FCC should adopt consistent policies that create incentives to move away from TDM.


  • SHAKEN is working as intended where implemented.
  • It’s premature to evaluate SHAKEN efficacy.
    • Small provider extensions are still in place.
    • Need consensus on token access and third-party authentication.
  • Lack of IP interconnections is one of the greatest challenges

Transaction Network Services, Inc.

  • STIR/SHAKEN usage is increasing. In first half of 2022, more than 63% of wanted intercarrier calls were signed.
  • Too many calls are signed with full A-level attestation that do not appear to justify it.
  • Some calls with A-level attestation also had invalid calling numbers.
    • 58% were from VoIP provider networks, 17% from wireline network, 25% other networks.
  • The Commission should empower the industry to self-police improper attestations.
  • The Enforcement Bureau should investigate providers that make unsupported attestations.
  • Third party signers should only sign calls on behalf of the originating provider should only do so with the originating provider’s token.
  • The Commission should encourage industry to develop a better definition of the ORIGID field.


  • Ensuring integrity of STIR/SHAKEN attestations will require action on two fronts:
    1. Covering most call attestations with either A- or B-level attestations,
    2. Accurately assigning the appropriate level of trust using objective standards and best practices.
  • C-level attestations do not provide helpful or actionable information that is not already available through traceback and may undermine STIR/SHAKEN.
  • The Commission should take enforcement action against providers who improperly assign A or B level attestations to calls that lack the requisite information.
  • The Commission should focus its enforcement efforts on identify and pursuing originating providers that fail to sign their traffic or that sign A or B attestations but do not know the identities of callers.
  • STIR/SHAKEN must be deployed in conjunction with:
    • Call blocking
    • Call labeling
    • Traceback
    • Robust Know-Your-Customer programs.


  • At least a portion of the efficacy assessment should be on preventing robocalls not just caller ID authentication.
  • The Commission could improve SHAKEN efficacy by enforcing these rules:
    1. Originating providers must sign their calls.
    2. All providers must prevent the use of their network for illegal robocalls.
  • ZipDX supports a rapid transition to an all-IP network and the adoption of SHAKEN-over-TDM solutions.
  • There are intermediate providers that wrongly put B attestation on calls that should be signed with C attestation.
  • It would be better if the originating provider signed these calls.
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