Replies to proposed FCC rules on robocall blocking

Thirty-four organizations filed replies to the first round of comments on the FCC Declaratory Ruling and Third Further Notice of Proposed Rulemaking (FNPRM) regarding robocall blocking and SHAKEN/STIR deployment. Here’s a summary of their replies.


  • Urged the Commission to move conservatively in establishing safe harbor for call blocking until SHAKEN/STIR is widely available to voice service providers and their customers.
  • Support requirements for prompt deployment of SHAKEN/STIR
  • Safe harbor for call blocking based upon “reasonable analytics” would require the Commission to adopt analytics best practices as part of the safe harbor. “The Commission should not absolve service providers of the risk that aggressive call-blocking analytics will impose on callers.”
  • Some service provider safe harbor proposals would encourage overly aggressive blocking
  • Critical calls list generates complex issues, including the vague definitions of “reasonable analytics” and “critical calls”
  • Unwanted calls should also be clearly defined
  • Blocking and unblocking should be free of charge

ACA Connects

  • SHAKEN/STIR mandate is unnecessary and would be burdensome to smaller operators and legacy networks
  • Support narrow safe harbor, but only for providers who have implemented SHAKEN/STIR

ADT Security Services

  • Critical call lists should include calls from alarm company central stations
  • The Commission should require call blocking programs to include a mechanism to remove erroneous blocks
  • Call blocking programs, especially if afforded safe harbor from liability, must be coupled with transparent, effective and fast mechanisms to reverse erroneous blocking

AFSA - American Financial Services Association

  • Important, time-sensitive calls that legitimate businesses place to their customers should not be blocked by voice service providers
  • The Commission should either (1) designate account servicing calls from financial institutions as critical calls, or (2) designate certain types of businesses as critical callers whose communications with their customers may not be blocked

AICC - Alarm Industry Communications Committee

  • The Commission should require measures to ensure that calls from alarm central stations are never blocked by voice service providers, such as by including calls from alarm central stations in a Critical Call List
  • Alarm companies must be able to easily correct any errors made by the voice service provider when blocking calls
  • The Commission should not grant broad safe harbor protections to voice service providers that block calls without the customer’s consent


  • There is overwhelming support for a broad safe harbor
  • Safe harbor should balance flexibility, effective call blocking, and limiting false positives
  • The Commission should be skeptical of proposals to narrow safe harbor, and opt-out default blocking should not be sunset
  • Critical Calls should be protected, but proposals to do this require further analysis

Cloud Communications Alliance

  • It is premature to establish a safe harbor for blocking calls based upon SHAKEN/STIR
  • Delegation and TDM network issues have not yet been resolved
  • Technical issues may prevent the transmission of tokens across even purely SIP networks
  • Any call blocking programs must include an effective challenge mechanism—this should be a requirement for any safe harbor protection
  • An effective redress mechanism is integral to ensuring that SHAKEN/STIR is implemented in a non-discriminatory and competitively neutral manner
  • The ability for major carriers to authenticate and verify calls within their network or with other major carriers should not be allowed to become a competitive advantage while standards such as certificate delegation, out-of-band transmission of tokens and other processes needed for more universal implementation are being developed and tested.

Consumer Reports et al

  • The Critical Calls List should be centralized and limited to government calls only, with a limited number of exceptions for genuine emergency numbers
  • Consumers should have personal whitelists
  • The FCC should establish a centralized system to manage unblocking emergency numbers and other unblocking requests
  • Opt-out call blocking should not be delayed pending full SHAKEN/STIR implementation

Credit Union National Association

  • Requests for broad safe harbor are premature. Call blocking should be based upon multiple inputs, including SHAKEN/STIR and reasonable analytics.
  • The Commission should refrain from adopting any safe harbors at this time
  • Robust challenge mechanisms should accompany any call blocking program
  • The Commission should establish a centralized Critical Calls List that includes fraud alerts and other vital, time-sensitive financial information
  • The Commission has no authority to authorize blocking of legal calls


  • Broad safe harbor is necessary
  • The wireless industry is committed to the completion of legitimate, wanted and critical calls
  • Providers need flexibility to respond to consumer feedback about completing legitimate calls
  • Critical calls need to be protected
  • The Commission’s opt-out declaratory ruling is crucial to the fight against illegal and unwanted robocalls


  • Efforts to curtail illegal or unwanted robocalls should not interfere with the authorized call reminding a diabetic patient to refill his or her life-sustaining insulin medication, the call informing a new mother how to schedule a well-child visit for her newborn, or the millions of other appropriate (and often automated) calls that healthcare providers and payers place to consumers every day.
  • HMS suggests that the Commission coordinate default call blocking with the implementation of SHAKEN/STIR. Once SHAKEN/STIR is fully implemented, HMS asks the FCC to only allow default call blocking programs to block those calls not authenticated under SHAKEN/STIR or block only those calls that the voice service provider has a high degree of certainty are in fact illegal.
  • “Reasonable analytics” has the potential to be a vague and unworkable standard
  • Healthcare calls serve a broad-based public health and safety interest and should qualify as critical calls
  • HMS requests that voice service providers give notice via an intercept message or special information tone that conveys a call has been blocked
  • The Commission should create a mechanism to provide information to consumers about the effectiveness of providers’ robocall solutions
  • Safe harbor should be afforded only when SHAKEN/STIR is fully implemented


  • The Commission should defer safe harbor for call blocking until industry resolves remaining challenges with SHAKEN/STIR
  • The Commission can measure the effectiveness of robocall solutions by requiring providers to report data on false positives

Inmate Calling Solutions

  • They provide telephone software that includes automated voice prompts and are concerned that robocall prevention measures should not automatically block calls made through their systems


  • The Commission should adopt a broad safe harbor
  • Safe harbor should not rely solely on SHAKEN/STIR, which would cause over-blocking
  • Safe harbor should cover robocall blocking programs based on reasonable analytics
  • The Commission should defer SHAKEN/STIR mandates pending imminent legislation
  • Smaller providers should have a later timetable for implementing SHAKEN/STIR
  • Mandatory SHAKEN/STIR implementation requires cost recovery

NCTA – The Internet and Television Association

  • Flexible implementation process for SHAKEN/STIR, broad safe harbor for providers that use SHAKEN/STIR in conjunction with a reasonable analytics program are essential for granting providers the regulatory certainty needed to deploy meaningful efforts to block unlawful and unwanted robocalls
  • NCTA opposes suggestions by NTCA (The Rural Broadband Association) for interconnection and transport rules that the NCTA deems would represent an unwarranted windfall to these companies
  • SHAKEN/STIR should not be mandated by the FCC
  • A centralized Critical Calls List should be compiled


  • The Commission should adopt a broad safe harbor for providers that block calls based on analytics that incorporate SHAKEN/STIR authentication
  • Callers must receive notification when their calls are blocked to enable unblocking of wanted calls
  • Major providers should be able to implement SHAKEN/STIR by the end of 2019
  • Significant SHAKEN/STIR implementation issues remain, including delegated certificates and legacy networks

Noble Systems

  • There seemed to be consensus in first round of comments on the FNPRM that both calling and called party need to be informed when a call is blocked
  • There also seems to be consensus that blocking solely on the SHAKEN/STIR verification outcome may be premature and undesirable
  • There is not consensus on either the need to measure the effectiveness of blocking or the Critical Calls List
  • Noble Systems advocates a requirement to collect data to measure the effectiveness of call blocking
  • Noble Systems believes that the Commission should study the implications and costs of a Critical Calls List and consider funding mechanisms to pay for it

Quicken Loans

  • Voice service providers should not block unsigned calls
  • Blocking calls by default, without an error correction process, and before SHAKEN/STIR is implemented, may have unintended consequences
  • Without full implementation of SHAKEN/STIR, the massive expansion of call blocking is likely to frustrate good-faith actors, endanger consumers, and increase the worst kinds of spoofing. Moreover, it will create an unjust and unreasonable state of broad and potentially capricious call blocking
  • Quicken Loans urges the Commission direct providers to focus their energy on fully implementing SHAKEN/STIR
  • Absent spoofing prevention, expansion of existing call blocking tools is unjust and unreasonable
  • The purpose of Critical Call Lists is thwarted if spoofing continues
  • The Commission should make full implementation of SHAKEN/STIR its primary focus


  • The efficacy and accuracy of the SHAKEN/STIR framework has not been fully implemented or tested, and the extent of deleterious call blocking of legitimate calls is unknown
  • Therefore, R1 urges the Commission to require that any voice service provider wishing to rely on safe harbor must also undergo regular audits of the accuracy of their call blocking program, establish controls to prevent false positives, demonstrate reasonable efforts to remediate false positives, and be disqualified from safe harbor if they fail to investigate false positives within a specified time period
  • R1 urges the Commission to establish protections for legal calls and prohibit the blocking of calls pertaining to important healthcare information


  • Significant policy, technical and implementation questions remain about SHAKEN/STIR, so the Commission needs to require that these gaps be addressed before opening the floodgates to call blocking
  • These gaps put legitimate calls at risk of being blocked
  • Competitive providers that are unable to fully sign calls or that otherwise cannot participate in the framework may no longer offer a viable, competitive option for an enterprise or other caller
  • The FCC should help establish standards for notice and redress
  • Divergent views on the Critical Calls List demonstrate that moving forward would be premature

Securus Technologies

  • A safe harbor based solely on SHAKEN/STIR would harm consumers
  • Any safe harbor must be accompanied by a requirement for voice service providers to implement a mechanism to correct erroneous call blocks
  • The Commission should seek focused comment on establishing a Critical Calls List to ensure certain calls are never blocked

Sirius XM Radio

  • The Commission should reset its focus to illegal calls, not vague and subjective notions of unwanted calls
  • The Commission must provide additional guidance for carrier call blocking program to ensure that lawful calls are not unreasonably blocked
  • Call blocking programs must have a mechanism to notify callers immediately when their calls are blocked
  • Carriers must have redress mechanisms to resolve over-blocking complaints
  • The Commission should task an advisory committee to work through key issues

Smithville Telephone

  • Smithville quoted testimony from the Small Provider Panel at the Robocall Summit that estimated the costs of implementing and running SHAKEN/STIR at hundreds of thousands of dollars up front and hundreds of thousands of dollars per year.
  • Given indication that the costs of implementation and operation of robocall mitigation is very high and suggestions that this should be cost-free to all beneficiaries, Smithville hopes for “some magical or innovative less costly solution”
  • Gateway attestation and out-of-band SHAKEN might underpin a new and affordable approach to robocall mitigation

Spoofcard LLC

  • They’re opposed to blocking unsigned calls
  • They urge the Commission to reconsider whether to allow call blocking based on failure of SHAKEN/STIR authentication until there is near-universal implementation
  • Carrier-based blocking based upon SHAKEN/STIR authentication will expand the incentives and opportunity for anti-competitive conduct by larger voice service providers who will be the first to implement SHAKEN/STIR
  • The Commission should not create a safe harbor for blocking calls that fail SHAKEN/STIR authentication

State Attorneys General representing 50 states and Washington D.C.

  • They agree with default call blocking based upon reasonable analytics and that still safeguards emergency numbers and calls to rural areas
  • Call blocking should be provided to consumers free of charge
  • They support Chairman Pai’s proposal to take appropriate regulatory action if major voice service providers do not voluntarily implement SHAKEN/STIR by the end of 2019
  • They also support prohibiting U.S.-based service providers from accepting voice traffic from any other provider if that other provider has failed to certify to the Commission that it complies with SHAKEN/STIR


  • The use of substitute caller ID information can be legitimate and such calls must not be blocked, for example, 8YY origination service for call centers
  • Not all calls with missing caller ID information are bad calls
  • SHAKEN/STIR must accommodate the role of call aggregation in the market


  • SHAKEN/STIR must be modified to address the least cost routing and enterprise business use cases so legitimate calls are not blocked and competition is not stifled
  • SHAKEN/STIR will not be effective unless pursued in parallel with IP interconnection
  • Telnyx has been quoted required minimum commitments of 100 million monthly minutes from a large incumbent simply to open discussions about an IP interconnection
  • Many VoIP providers are unaware as to how their downstream vendors interconnect with large incumbents—calls can cross TDM segments, for example

TelTech Systems

  • The Commission should not create a safe harbor for blocking calls that fail SHAKEN/STIR authentication
  • The Commission should consider creating a safe harbor for network-wide blocking based on reasonable analytics
  • Critical Call Lists are not currently available and would be difficult to compile, resulting in the potential to accidentally block emergency numbers


  • FCC rules permit the blocking of illegal calls
  • The Commission should establish a sufficiently broad safe harbor for call blocking
  • The Commission must develop a Critical Call List

USTelecom – The Broadband Association

  • USTelecom urges the Commission to continue its “flexibility” and “a diversity of approaches” to stopping illegal and unwanted calls
  • Safe harbor based solely on the SHAKEN/STIR protocol is too narrow—providers need the ability to use any reasonable call blocking tools, and the Commission should broaden safe harbor
  • The Commission should avoid prescriptive mandates to implement SHAKEN/STIR
  • The Commission should provide an exemption to providers using TDM facilities or adopt a staggered timetable for SHAKEN/STIR implementation
  • Critical Call List may not be necessary at this time—the best path forward for industry to prevent blocking emergency calls is for voice service providers to adopt SHAKEN/STIR
  • If a Critical Calls List is developed, it should be centrally maintained


  • Providers need flexibility to configure and deploy blocking tools in the ways that most effectively meet consumer demands
  • Consumers would benefit from safe harbor for service providers that engage in call blocking, as long as the providers reasonably use analytics that incorporate SHAKEN/STIR
  • The Commission should stand ready to step in and ensure that providers promptly start embracing SHAKEN/STIR
  • The Commission should require providers who do not implement SHAKEN/STIR to certify that they do not originate illegal robocalls, and such certifications should be tracked in a publicly available registry
  • The Commission should prohibit improper or sloppy signing of calls with SHAKEN/STIR

West Telecom Services

  • The Commission should extend the SHAKEN/STIR deadline, at least for smaller providers
  • Default opt-out blocking programs should not be permitted to employ discriminatory blocking tactics, including the lack of SHAKEN/STIR authentication
  • The Commission should permit default opt-out blocking only of illegal and malevolent calls
  • The Commission should deny carte blanche safe harbor in order to minimize over-blocking

Wolters Kluwer

  • Wolters Kluwer are concerned that implementation of new call authentication technology by voice service providers will mistakenly block lawful interactive voice response (IVR) calls made to patients to help manage their health
  • The Declaratory Ruling did not include specific instructions and requirements for voice service providers to identify and exempt legitimate callers prior to implementing SHAKEN/STIR.


  • There are barriers outside of rural local exchange carriers’ control that prevent them from adopting SHAKEN/STIR
  • Many are reliant on interconnection arrangements that force them to transmit and receive voice traffic in legacy TDM format
  • Safe harbor for call blocking must be narrow and should not allow for blocking calls that lack authentication

TransNexus comments

We filed comments in the initial round but did not file reply to comments. However, in reviewing these highlights, we have a few remarks to offer.

There is a difference between blocking unsigned calls and blocking signed calls that fail SHAKEN/STIR verification

We interpret the FNPRM to advocate blocking signed calls that fail verification, not unsigned calls.

Several of the replies expressed concern about blocking unsigned calls. Obviously, voice service providers would not have any interest in doing that unless and until SHAKEN/STIR becomes ubiquitous.

Several replies expressed concern over the vagueness of the term “reasonable analytics.”

We understand this concern. Here’s an example of what we would consider reasonable:

  1. A voice service provider implements SHAKEN/STIR and phone number reputation lookup.
  2. SHAKEN/STIR verification confirms that a calling number is not spoofed.
  3. Phone number reputation lookup reveals that the calling number has been widely reported as a spammer.
  4. We think it would be reasonable for the terminating voice service provider to give their subscribers the option to either block such a call, divert it to voicemail, or divert it to a CAPTCHA device to prompt for human interaction.

Cost concerns

Smithville Telephone Company cited testimony at the Robocall Summit that SHAKEN/STIR solutions cost $100,000 or more to implement and another $100,000 per year, every year, to run. Jim Dalton, TransNexus CEO, participated in the Summit, heard that testimony, and testified that SHAKEN/STIR is not expensive. But apparently, the exorbitant cost estimate stuck.

TransNexus is providing SHAKEN/STIR service to all our customers free of charge through the end of 2019, until the STI-PA and STI-CAs are up and running.

Once the governance authority and certificate authorities are up and running, we will begin charging customers who wish to use SHAKEN/STIR services. These fees vary by call volume, but we don’t expect any of our customers, even the very largest, to incur fees anywhere close to the costs quoted in the Robocall Summit.

We would be happy to provide a cost estimate for any voice service provider no matter how large or small.

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Lots of replies to the FCC robocall blocking FNPRM