Reply comments on FCC proposed rules for non-IP SHAKEN

The FCC received a variety of reply comments on its proposed mandate for non-IP call authentication. This article summarizes the filings and themes.

Recurring themes

Here are a few recurring themes we noticed in these reply comments:

Reply comments

There were 124 pages of reply comments from ten submissions. We’ve summarized these comments below, with a focus on new information not provided in the first round of comments. If you’d like to see more information, you can click the filer’s name above each summary to read that organization’s filing.

Competitive Carriers Association

• Agrees with NCTA that implementing non-IP call authentication undermines the more important objective of completing the IP transition.
• Many providers would like to finalize the IP transition, but can’t because of anticompetitive activity by some large interconnecting carriers.
• The Commission should ensure that IP transition costs don’t disproportionately fall on smaller carriers, establish a working group to study the IP transition, affirm that IP interconnection is protected, establish default interconnection locations, and prohibit TDM access charges where IP interconnection is refused without a valid technical justification.

CTIA

• Deploying non-IP call authentication solutions would hinder the IP transition.
• Non-IP solutions raise security and interoperability concerns.
• The Commission should focus on the IP transition.

GCI Communications Corp.

• The Commission should encourage and support the IP transition.
• IP transition takes significant resources and time.
• Many rural end offices in Alaska do not have SS7 capability. It would be impossible to implement In-Band without significant equipment upgrades.
• Bilateral agreements would be difficult to implement with the current interconnection agreements. Even a single link not covered by a bilateral agreement will break transitive trust.
• Out-of-Band would be unreasonably burdensome to implement and would require substantial upgrades to legacy equipment.
• Out-of-Band allows bad actors to mimic legitimate calls by intercepting credentials.
• If a non-IP mandate is adopted, a longer implementation timeline is required, no shorter than 24 months, and potentially longer for non-nationwide carriers.

Transaction Network Services, Inc.

• Out-of-Band race conditions and other vulnerabilities can occur because information is published to a public Call Placement Service (CPS).
  • A private CPS is significantly more secure.
  • The Commission should not regulate private CPSs in a way that would negate the benefits they provide.
• The Commission should ignore the discussion of call labeling in this proceeding.
• The Commission must address outstanding issues with over-attestation.
  • Too many calls are authenticated with an inappropriate A-level attestation despite invalid calling numbers, DNO calling numbers, and other issues.
  • Certain top-tier carriers marked 8% of invalid number calls with A-level attestation in the first half of 2025.
  • Non-top-tier carriers marked 57% of their invalid number calls with A-level attestation in the same period.

TransNexus

• The percentage of calls at termination with authentication intact continues to drop. Non-IP call authentication is sorely needed.
• Reviewed the Out-of-Band Multiple STI-CPS and Agreed STI-CPS mechanisms in some detail to provide background understanding for the comments that followed.
• The Commission has a legal obligation to mandate effective non-IP call authentication. We find no legal authority for the Commission to mandate an IP transition. The Commission cannot fail to take action required by law and instead prioritize a cause for which it has neither legal authority nor a legal obligation.
• Contrary to the claims of some other commenters,
  • Out-of-Band protects CPNI, and its use of CPNI is appropriate.
  • Out-of-Band mechanisms are secure.
  • Out-of-Band Agreed STI-CPS supports the use of a private CPS.
• The “ubiquitous implementation” concern of some commenters is misunderstood and misrepresented.
  • Providers need to support and implement an approach that is supported by the service providers they interconnect with.

USTelecom-The Broadband Association

• The FCC should not mandate the proposed In-Band and Out-of-Band solutions. The solutions have many shortcomings, and advocates for the methods don’t have to implement them.
• Market-based solutions satisfy the TRACED Act.
• The Commission should promote the IP transition, but without either an express or de facto mandate.
  • The IP transition has complex issues beyond the scope of call authentication.

Verizon

• The proposed mandate assumes all providers have the option to migrate to IP within two years. This is not correct.
  • In 8 of the 10 jurisdictions where Verizon is the ILEC, there are significant legal and regulatory hurdles standing in the way of IP transition. The mandate would force Verizon and other similarly situated providers to implement non-IP solutions.
• Any Commission policy that either directly or de facto mandates IP transition must include a reasonable transition period and account for TDM legal obligations.
  • For Verizon, the IP transition will take significantly longer than 2 years.
• The Commission should conclude that providers making IPVS available satisfy any non-IP call authentication the Commission imposes.
• The non-IP solutions are not reasonably available. They are not interoperable. Every carrier would need to support every method simultaneously. They have issues with CPNI privacy and race condition security.
• Allowing providers to choose which non-IP solution they implement would complicate years of messy implementation negotiations. The IP transition would be far in the rearview mirror by the time the non-IP solution assumptions could be solved.
• The Commission must make further reforms to STIR/SHAKEN, e.g., by pursuing providers that sign calls with inappropriate A-level attestation, letting providers block calls more aggressively, and considering whether the B-level attestation helps or harms.
• Also submitted a declaration from their director of network planning.

Voice on the Net Coalition

• The FCC should mandate that networks upgrade to IP by December 31, 2028, or two years after the effective date of rules in this proceeding, whichever is later.
• The Commission should convene a working group to address network interconnection.
• The Commission should not adopt unreliable solutions that will be obsolete before they are implemented.

WTA – Advocates for Rural Broadband

• Given the TRACED Act’s explicit recognition of the use of non-IP solutions, the Commission cannot simply mandate that all carriers transition to IP networks.
• WTA agrees with the Commission that In-Band and Out-of-Band Multiple STI-CPS are both developed and reasonably available.
• Out-of-Band does not make it likely for bad actors to be able to hijack legitimate STIR/SHAKEN credentials and present fraudulent calls as legitimate.
• WTA supports the proposed two-year period for companies to either migrate to IP or adopt one of the specified non-IP frameworks, so long as the Commission allows waivers if a company can demonstrate that it needs more time.
  • The Commission generally has the authority to waive its rules for good cause shown. In addition, the TRACED Act in Section 5 gives the Commission authority to delay implementation for small and rural providers.
• The Commission should not accelerate the transition period ahead of what is reasonable for a rural carrier, given their limited number of employees and much smaller budgets.
  • Unless the Commission can provide or identify subsidies to pay for an accelerated IP transition, one year will not be sufficient time for many small companies to implement IP networks.

ZipDX LLC

• The Commission must quantify the scope of the problem before moving forward.
• The Commission should convene a working group to address the IP transition.
• Proposed actions:
  • Eliminate the non-IP exemption for TDM within an intermediate provider’s own network.
  • Declare non-IP exemption inapplicable to TDM emulation.
  • Require the registered traceback consortium to collect and share instances where the originating authentication is lost.
  • Require providers to prioritize routing over paths that support SHAKEN.
  • Revise regulations that prevent or discourage IP transition.
  • Require providers that accept unsigned calls to report monthly.
  • Establish a date certain when the TDM exemption will be eliminated.
  • Revise rules for call authentication of foreign-originated calls.

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