Call analytics and robocall mitigation firm Transaction Network Services (TNS) says that the main takeaway from the 2026 Robocall Investigation Report is that the Secure Telephone Identity Revisited and Signature-based Handling of Asserted Information Using toKENs (STIR/SHAKEN) protocol implementation progress is threatened by smaller carriers. This group risks falling behind in the transition from legacy to IP networks.

TNS found that smaller providers’ budgets impact modernization. Signed call traffic between smaller service providers was only 17.5% during 2025. This provided scammers with hiding places for unwanted robocall call traffic. Limited bandwidth, staffing and tech support have been major obstacles to migrate away from legacy infrastructure.

Other highlights from the report, which is based on more than 1.5 billion daily robocall events across hundreds of carrier networks:

• Tier 1 robocall mitigation efforts are strong, but plateauing. Eighty-five percent of all traffic between Tier 1 carriers — AT&T, Charter, Comcast, Lumen, T-Mobile, UScellular, and Verizon — was signed in 2025, with 93% signed with the highest “A-level” attestation. These numbers are on par with the prior year.
• Scammers are adapting faster than defenses: Bad actors are shifting to techniques such as SIM boxing and multimodal scams to originate traffic that appears legitimate but actually is part of increasingly sophisticated fraud campaigns that are harder for consumers to distinguish from legitimate calls.
• Escalating artificial intelligence (AI)-enabled fraud: The report found that four out of five Americans believe imposter robocall scams increased in 2025, and 77% are very concerned AI can be used to convincingly impersonate their voice or identity. This underscores the need for analytics, Know Your Customer (KYC) and post-STIR/SHAKEN defenses.

“Successful STIR/SHAKEN implementations and proactive investments in network modernization have propelled Tier-1 carriers to a strong position in the battle against unwanted robocalls,” TNS Communications Market’s General Manager of Communications Market Seth Walton said in a press release about the report.

“While smaller carriers face a fundamentally different financial calculus, the progress by Tier-1 carriers reflected in our report signals that commitment to robocall mitigation beyond ‘minimal compliance’ efforts can yield tangible and sustained operational, business, and customer satisfaction benefits.”