Smaller carriers improving signed call traffic, but interconnectivity challenges threaten STIR/SHAKEN (Reader Forum)

Since being introduced via the TRACED Act, STIR/SHAKEN has been a key driver in the telecom industry’s fight against robocalls. The STIR/SHAKEN framework is the telecom industry’s standard call authentication technology. It provides carriers’ subscribers with peace of mind that callers are who they say they are, diminishing the number of spoofed calls.

When the Federal Communications Commission (FCC) adopted STIR/SHAKEN in 2020, the goal was for Tier-1 carriers to implement the protocol by June 2021 and smaller carriers by June 2022. The staggered deadline dates, in part, acknowledge that smaller carriers face a different set of cost and resource realities to migrate from legacy to IP networks and fully deploy STIR/SHAKEN.

As smaller carriers navigate this transition, the telecom industry faces a critical transition period that requires all stakeholders to support network transformation efforts to get the most out of STIR/SHAKEN. This transition is key to maximizing the effectiveness of STIR/SHAKEN.

Smaller carriers’ STIR/SHAKEN push yields mixed results

After being granted a two-year extension to implement STIR/SHAKEN protocols into their networks (June 30, 2023), smaller carriers have had additional time to fine-tune their capabilities to properly sign call traffic.

TNS’ most recent Half Year 2024 Robocall Investigation Report data suggest positive trends but that these efforts remain a work in progress. On one hand, the percentage of smaller carriers’ signed call traffic has improved: 30 percent of call traffic between non-top seven carriers is now signed with STIR/SHAKEN protocols, up from 22% in 2023.

Conversely, they still trail top-tier carriers by a significant margin. The top seven carriers (Verizon, UScellular, T-Mobile, Lumen, Comcast, Charter and AT&T) signed 85% of all calls between themselves while total signed call traffic for all operators remained steady at 75%.

STIR/SHAKEN efforts will continue, but the robocall mitigation story must also progress to the next chapter – addressing interconnectivity challenges that blunt the full benefits of STIR/SHAKEN and provide opportunities for bad actors to launch robocall attacks.

Providing any opening for bad actors can be costly. As technology rapidly improves, scam artists continue to find new ways to launch sophisticated robocall attacks. Multi-faceted threats — including Generative AI deepfake voice cloning — raise the stakes and make it imperative that all telco stakeholders stay proactive in robocall mitigation efforts. 

To maintain hard-fought progress, there are steps core stakeholder groups (carriers, industry, regulators, policymakers and consumers) should consider:

Smaller carriers must address SIP breakage

Digital transformation is happening outside of Tier-1 carriers, but it tends to be a slower process. Smaller carriers’ interconnectivity issues largely stem from their reliance on legacy TDM equipment, specifically their tandem switches and circuits. Even in SIP to SIP networks and where smaller carriers have moved forward with STIR/SHAKEN, call signing is disrupted by legacy tandem hops. When the destination carrier receives the call traffic, it is not signed which undermines the value STIR/SHAKEN is designed to deliver.

Smaller carriers can expand their SIP interconnectivity and blunt the impact of SIP breakage by deploying authentication solutions. These solutions enable them to tap into advanced call mitigation capabilities such as branded calling. Bypassing connectivity challenges with SIP to SIP peering makes digital transformation possible — even if the smaller carrier hasn’t fully migrated to IP networks.

Regulators can foster achievable network transformation

Continuing to enable smaller carrier SIP network transitions is vital. There is also a need to acknowledge the budget challenges smaller carriers face in undertaking digital transformation efforts. Carrier data affirm that increasing terminating call signing will benefit from advancing industry solutions that deliver ubiquitous connectivity so that a non-Tier-1 carrier can reach thousands of networks without having to peer with each one individually.   

A rising tide can lift Tier-1 boats

Despite the continued progress Tier-1 operators have made with signed calls, robocalls persist. To limit the number of unwanted robocalls, the top carriers should remain invested in the overall efficiency of STIR/SHAKEN, as broader consumer frustration and exposure to scams can negatively impact the telecom industry.

There has been undeniable progress made in robocall mitigation over the last five years. And yet, if smaller carriers continue to put off network transformation investments, a more robust STIR/SHAKEN will remain far out of reach and opportunities for robocall bad actors will remain.

When the entire telecom industry unites to enable smaller carriers’ migration to IP and optimize STIR/SHAKEN, consumer trust in the voice channel can be restored.