Comments on the FCC non-IP call authentication inquiry

The FCC issued a Notice of Inquiry to ask for comments on non-IP call authentication. This is a hot topic, and the Commission received 161 pages of comments in 20 submissions. In this article, we summarize the comments and recurring themes.

Recurring themes

  • 75% of comment filings were in favor of the Commission requiring providers that rely on non-IP technology to either transition to IP or implement a standardized non-IP solution.
  • Those opposed to the non-IP methods preferred the Commission accelerate the IP transition.
  • Comments from several small providers and industry associations said that they have incurred the cost and spent the time to implement STIR/SHAKEN yet call authentication information is lost at non-IP barriers along the call path. Calls they originate arrive unsigned, and calls they receive are unsigned. Intermediate providers using non-IP technology should have to support STIR/SHAKEN too.
  • Several commenters suggested intermediate providers using non-IP technology should either migrate to IP or deploy non-IP solutions by June 30, 2023.
  • Several comments opposed to the non-IP methods were concerned that these methods have security issues and are not scalable for large networks.
  • Some thought that use of the non-IP methods might slow the IP transition. Others thought that phasing out the non-IP extension might accelerate the IP transition.


There were 161 pages of comments in 20 submissions representing 27 entities (one submission was a joint filing). There were many interesting points raised in these comments. Here are summaries of each. You can click the filer’s name above each summary to read that organization’s filing.

Some of these summaries are rather long! We decided to err on the side of including more points raised in the comments rather than trying to keep the summaries as short as possible and risk omitting important points of discussion.

ABA Joint Trades

  • The eight organizations (the “Associations”) participating in this joint filing strongly support the Commission’s efforts to implement caller ID authentication on non-IP networks.
  • The presence of non-IP networks is substantially undermining the STIR/SHAKEN framework.
  • The Associations urge the Commission to require non-IP network providers to implement a commercially available solution as soon as practicable.
  • The Associations take no position on which of the available technologies should be used. It may be appropriate to allow non-IP providers to adopt a solution that works best for them, as long as the solution transmits information regarding caller ID authenticity to the terminating provider. The requirement should apply to all non-IP providers in the call chain.

Carolina Digital Phone Inc

  • Carolina Digital Phone signs 100% of its calls with STIR/SHAKEN. They estimate that SHAKEN information survives transit on less than 20% of their calls.
  • Because of this, their end users’ calls are being flagged as spam and in many cases are blocked because the SHAKEN information does not survive transit across the network.
  • They demand that the FCC require every network operator to implement SHAKEN by June 2023, as solutions are available today for TDM networks as seen in ATIS-1000095 [Non-IP In-Band] and ATIS-1000096 [Out-of-Band].

Cloud Communications Alliance

  • The Commission should require non-IP network providers either to adopt a commercially available technology that enables the transfer of STIR/SHAKEN information or upgrade their networks to IP by June 30, 2023.
  • Cloud Communications Alliance members have invested substantial capital and human resources to implement STIR/SHAKEN. Their investment and resources have been squandered by the continuing presence of non-IP networks in the call path.
  • The Commission should not wait for the IP transition.
  • The Commission has the legal authority to mandate non-IP call authentication

Competitive Carriers Association

  • The FCC should remove obstacles to the IP transition rather than impose additional obligations on carriers with TDM networks.
  • In negotiations with legacy ILECs, CCA members encounter significant resistance to the proposition of routing calls using IP-based tandem switches rather than TDM.
  • Implementing the non-IP ATIS standards would require significant changes to existing non-IP networks. Requiring such investments of time and resources would diminish the incentive to transition to IP. Improved call authentication would no longer be an inducement to transition.

ElliCom, Inc.

  • ElliCom has made a significant investment in SHAKEN to be in compliance and to ensure that its clients receive the absolute best service possible.
  • Our clients’ calls don’t always go through or are mislabeled as spam. We believe this is because the SHAKEN PASSporTs are being dropped by TDM networks in the call path.
  • ElliCom’s network is ready for SHAKEN for TDM today.
  • Large carriers don’t have to do anything but can interfere with the transmission of the SHAKEN data by not passing it through their TDM networks. This is frustrating.
  • All carriers should be implementing SHAKEN.

Freshphone, Inc.

  • Freshphone asks the FCC to require any non-IP carrier to be in full compliance with STIR/SHAKEN by June 2023.
  • The exemption for TDM networks breaks the entire STIR/SHAKEN ecosystem, perpetuates robocalls and provides anti-competitive effects that harm consumers.
  • STIR/SHAKEN does not work and will remain defective until non-IP networks are required to comply with STIR/SHAKEN.
  • The FCC should end the non-IP exemption and require any non-IP carrier to be in full compliance with STIR/SHAKEN by June 2023.

Iowa Network Services, Inc., d/b/a Aureon Network Services

  • Aureon provides Centralized Equal Access (CEA) service in Iowa. It connects interexchange carriers (IXCs) with rural local exchange carriers (LECs). Aureon has been in the process of upgrading its tandem voice switch since 2015. The new switch, capable of both TDM and IP traffic, began operating in April 2020. All traffic will be transitioned to the new switch within the next two months. The duration of this process depends on the LECs that subtend Aureon’s network and who need to convert their interconnection to IP. This could take 24 months or longer to complete.
  • Aureon has no control over the method of connection used by IXCs. If they don’t use IP, the transition to IP will be further delayed.
    • For this reason, the Commission should mandate SIP connection with intermediate carriers if their networks are ready to accept and transmit IP calls.
  • Out-of-Band would be far easier to implement than Non-IP In-Band. The logistics of ensuring that all the necessary agreements are in place for Non-IP In-Band are extremely burdensome and complex. Out-of-Band is a much simpler one-stop solution.
    • Out-of-Band is already available and can be readily and economically provided to non-IP-based carriers.
    • Out-of-Band solution providers have economies of scale by providing service to multiple voice service providers.
    • Out-of-Band could reduce disputes among carriers regarding transport costs.

Junction Cloud Connections

  • Calls that pass through a TDM network will reach the intended destination without the STIR/SHAKEN information. This diminishes the value of STIR/SHAKEN’s capabilities.
  • The biggest complaints that Junction Cloud Connections hears from affected customers is that they still receive robocalls and their outbound calls are mislabeled as “potential spam” because the STIR/SHAKEN PASSporT is dropped by TDM networks in the call path.


  • MDU1 expended quite a bit of time and money to meet the FCC requirement to support STIR/SHAKEN.
  • Some of our calls going to incumbent cellular networks never complete but go to voicemail. Calls from other cellular networks to the same cellular network complete correctly. Our customers are still getting robocalls. This is probably because the PASSPORT is being dropped in TDM networks.
  • We have just been made aware that large incumbents are pushing back to not support STIR/SHAKEN for their legacy TDM/POTS networks.
  • If MDU1 can implement STIR/SHAKEN with the limited resources we have, there should be no reason why an incumbent can’t do the same.
  • Solutions for TDM already exist: ATIS-1000095 and ATIS-1000096.
  • Every provider, no matter their size, should implement SHAKEN by June 2023.

NCTA - The Internet & Television Association

  • Terminating providers still receive billions of calls from upstream providers without authentication information. A major contributing factor is the refusal by the largest incumbent LECs (Verizon, AT&T, Frontier, and Lumen) to exchange traffic in IP.
  • NCTA encourages the Commission to take steps to encourage the IP transition and ensure that large incumbent LECs are not able to continue imposing the higher costs and inferiorities of TDM on IP voice providers and consumers.
  • The Commission should consider whether to require that large incumbent LECs accept traffic in IP from upstream IP voice providers and hand off traffic in IP when the next network in the call path is IP-based.
  • To the extent the Commission feels it may be necessary to also adopt a non-IP solution, the Commission should consider whether to require TDM providers to compensate IP providers for any costs incurred in implementing the non-IP solution.
    • It would be unreasonable for the Commission to force providers that have invested in IP networks and implemented STIR/SHAKEN to incur additional costs due to another provider’s failure to transition to IP.

NTCA-The Rural Broadband Association

  • Non-IP facilities operated by other providers stand in the way of rural LECs’ ability to do caller ID authentication.
  • To comply with the TRACED Act, the Commission must either mandate service provider use of non-IP standards or facilitate voice traffic over IP.
  • Published non-IP standards can enable the widespread availability of caller ID authentication.
  • Prioritization of the IP transition is the optimal path forward.
  • A non-IP mandate could be unnecessary if the Commission were to facilitate a transition away from non-IP interconnection arrangements.
  • The Commission should enact a “network edge” rule that preserves the current apportionment of costs for the exchange of voice traffic between RLECs and other operators. This would simply preserve the status quo with respect to cost apportionment.
  • The Commission should ease the regulatory burdens of transitioning away from non-IP facilities.

TelcoBridges Inc.

  • Providers utilizing non-IP legacy technology should be required to either upgrade their networks to IP or adopt caller ID authentication solutions that are commercially available and conform to standards promulgated by ATIS.
  • Even TelcoBridges customers that have transitioned their networks to IP often complain that they are unable to fully offer the benefits of STIR/SHAKEN to their customers because their calls cross a non-IP barrier somewhere along the call path.
  • The failure of non-IP providers to either upgrade their networks to IP or implement an alternative solution that preserves the STIR/SHAKEN attestation information is unfair and anti-competitive.
    • The largest carriers can provide the benefits of STIR/SHAKEN to their own customers while preventing smaller providers from similarly serving their customers.
  • Both Out-of-Band and in-band solutions consistent with ATIS standards are available at reasonable costs.
  • Providers can avoid having to implement one of the non-IP solutions by upgrading to an all-IP network.
  • The Commission should not wait for the IP transition or resolution of IP interconnection issues to close the STIR/SHAKEN gap created by the presence of non-IP networks.
  • The Commission should require non-IP network providers to either upgrade their networks to implement an available alternative solution within one year.

Think Simplicity Inc.

  • Approximately 80% of the calls coming into their network do not have a SHAKEN PASSporT.
  • STIR/SHAKEN is a failed initiative when any carrier opts out. SHAKEN only works when it is deployed by all network operators end to end without exception.
  • Since small SIP-based providers have implemented SHAKEN, large carriers with legacy networks should have the same SHAKEN compliance requirements for SPAM call mitigation to work.

  • Even though TRACI has made sure they are compliant in authenticating calls, SHAKEN is not working because TDM networks are not required to implement it.
  • Our efforts are failing when traffic passes TDM networks as the SHAKEN PASSporTs are dropped, resulting in customers still receiving robocalls and some of their outbound calls being mislabeled as SPAM or blocked.
  • There are two SHAKEN solutions available for TDM networks: SHAKEN for ISUP (ATIS-1000095) and Out-of-Band SHAKEN (ATIS-1000096).
  • Every network operator should implement SHAKEN by June 2023. There’s no excuse.
  • If small SIP-based service providers can implement SHAKEN, large carriers with legacy networks should also have the same SHAKEN compliance requirements.


  • The non-IP methods are not a new, different call authentication framework. They are alternative transport methods within the STIR/SHAKEN framework used to transport call authentication information through or around non-IP barriers.
  • TransNexus has real-world experience in helping voice service providers use Out-of-Band in their production networks. We did this by adding Out-of-Band features to our existing STIR/SHAKEN solutions. We also built a Call Placement Service, which we offer at no charge to any SHAKEN-authorized provider.
  • TransNexus has about 50 service provider customers using Out-of-Band.
  • Widespread use of tandem TDM switches creates a non-IP barrier. Larger providers inside this wall exchange a large portion of their calls with STIR/SHAKEN. Smaller providers outside of the non-IP barrier are able to exchange far fewer calls with STIR/SHAKEN information intact because of the non-IP barrier. Larger providers enjoy a 3-to-1 advantage in call authentication because of this non-IP barrier.
  • Because of this 3-to-1 disadvantage, providers outside of the non-IP barrier have more of their outgoing calls mislabeled or blocked. This harms their call completion. The non-IP barrier makes it more difficult for them to protect their subscribers from incoming robocalls. This is unfair, anti-competitive, and unnecessary.
  • We believe the Out-of-Band method is a better choice than Non-IP In-Band for most providers that rely on non-IP technology and are not yet ready or able to transition to IP.
  • The Commission should structure its rules such that originating voice service providers must authenticate caller ID with STIR/SHAKEN. Every provider along the call path must relay this authentication information to the terminating provider. The use of non-IP technology can no longer be an excuse to drop some or all of the SHAKEN information.
  • To comply, providers that rely on non-IP technology can either migrate to IP or use one or more of the standardized non-IP methods. The compliance test is whether they successfully relay the SHAKEN information they receive.

USTelecom–The Broadband Association

  • STIR/SHAKEN covers the vast majority of calls. Only a small portion of calls reach subscribers unsigned.
  • TDM networks are not a significant source of illegal calling campaigns.
  • The Commission should focus its efforts on promoting the transition to IP.
  • TDM in the middle is the most important barrier to overcome.
  • The SIP Interconnection Working Group report offers three options that address the TDM-in-the-middle challenge.
  • Out-of-Band only addresses TDM-in-the-middle, not TDM origination or termination.
  • TDM-reliance is already closing on its own, and fast.
  • The Commission should encourage the IP transition but refrain from mandating it.
  • The Commission should update its service discontinuance rules to streamline an ILEC’s ability to eliminate TDM-based service.
  • Non-IP proposals are unproven and will not scale to larger provider networks.
  • ATIS-1000073 describes problems with using the SS7 screening indicator parameter as specified in Non-IP In-Band.
  • The UUI SS7 parameter is currently in use for its originally designed purpose by some service providers.
  • Out-of-Band has security concerns, such as a bad actor listening to and analyzing call patterns, then generating replay attacks.


  • The best approach to protect consumers from illegal robocalls is to promote and encourage (though not mandate) the ongoing transition from non-IP to IP so that STIR/SHAKEN can better achieve its promise.
  • While non-IP authentication solutions show promise in some contexts, they do not yet meet the Commission’s threshold of being (1) fully developed and finalized by industry standards and (2) reasonably available.
  • Non-IP solutions have been deployed only in small or closed-system networks, and the major security, governance, and unanswered questions mean they are not scalable in larger networks like Verizon’s.
    • It may make sense for some providers to deploy these types of proposals, but the better way is to focus on developing and deploying new IP solutions that enable IP-based traffic exchange.
  • One solution that Verizon is helping develop enables providers to exchange small volume voice traffic over existing internet services.
  • Non-IP methods are not workable for large networks or widespread deployment.
  • Verizon will not adopt Out-of-Band or Non-IP In-Band because of security concerns.
    • With Out-of-Band, there are a variety of ways that bad actors can hijack legitimate STIR/SHAKEN credentials.
    • Non-IP In-Band would require providers to omit other call-identifying information in ways that could impact service and be confusing to end-user customers.

Verizon also included an exhibit with their comments.

Voice on the Net Coalition

  • The Commission should take the necessary steps to encourage the transition to all-IP networks.
  • VON does not support the adoption of non-IP authentication solutions. Doing so would eliminate incentives for other providers to transition to IP solutions.
  • VON participated in a “SIP Interconnection Working Group” that issued recommendations for small providers to exchange traffic in IP.
    • Each option has cost and quality of service considerations and relies on commercially negotiated agreements and service providers.
    • Commercial agreements may not always lead to palatable or equitable results for all parties and in some cases may not be available to providers with smaller volumes of traffic. This will be available next year. It lacks security concerns with current non-IP solutions.

WTA - Advocates for Rural Broadband

  • WTA urges the Commission to terminate the non-IP SHAKEN extension because Out-of-Band and Non-IP In-Band are fully developed and finalized and the underlying equipment and software necessary to implement them are reasonably available on the commercial market.
  • Many WTA members who have converted from TDM to IP cannot implement STIR/SHAKEN effectively because they must hand off their calls to an intermediate provider that uses a TDM access tandem that does not pass on the STIR/SHAKEN header.
  • Given that the compliance extension for small providers is scheduled to terminate on June 30, 2023, that would appear to be a reasonable date for at least beginning the phase-out of the non-IP extension.
  • This step would not only close the remaining gap in the caller ID authentication system but also would advance the ongoing transition to the IP network.
  • Increased implementation of STIR/SHAKEN will avoid the danger of increasing call completion problems affecting rural and other small service providers and the resulting undermining of the reasonably comparable service goals of Section 254(b) of the Communications Act.


  • Both ATIS standards for non-IP call authentication have merit. The burden of implementing a non-IP standard should fall on the providers that operate non-IP networks. They have a choice of implementing that non-IP authentication technology or transitioning to IP.
  • Those that continue to argue for ongoing delay need to start volunteering some constructive suggestions rather than just kicking the can down the road.
  • Are some providers perhaps arguing that, rather than directing money toward SHAKEN over TDM, it would be better to spend that money on the IP transition, but then they do not spend the money on that either?
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