October 14, 2026

STIR/SHAKEN Isn’t Enough: The Hidden Problem With Call Attestation Ratings

STIR/SHAKEN is designed to verify the origins of phone calls to a recipient’s cell phone. Think of it as a digital signature that helps validate the caller ID. However, the framework only verifies who signed the caller ID. Call attestation from STIR/SHAKEN verifies identity but not intent.

Call Attestation Ratings Are Important But Not Omnipotent

A call can be authenticated and still be unwanted, suspicious, spoofed, or incorrectly classified. Meanwhile, a legitimate business call can be authentic yet still be blocked or labeled as spam.

An A, B, or C rating simply verifies technical requirements. A caller with an A-level rating can still send spam calls by repeatedly calling consumers based on whatever automation is set up on the back end of a call database or CRM. Call centers must judge dialing patterns, call volume, and complaint rates with behavioral analytics.

What Is a Call Attestation Rating?

A call attestation rating is a trust score assigned under the STIR/SHAKEN framework to distinguish legitimate versus unverified call origination.

TransUnion states there are three levels of call attestation.

A-Level is full attestation, meaning the caller has an authenticated relationship with the consumer, provided the number, and originated the call from its network.
B-Level represents partial attestation, and it means the recipient is a customer, and the call originates from the company’s network. However, the company did not provide the phone number, even though the relationship is authenticated.
C-Level indicates gateway attestation, meaning that the call originates outside of the company’s network and that the recipient has no authenticated relationship with the caller. This is the lowest level of trust, and it can have negative consequences for your business.

What Is Call Attestation Designed to Do?

STIR/SHAKEN helps authenticate asserted caller-ID information. The framework tries to prove who makes the call, confirm control of the number, and make caller ID spoofing more difficult.

However, STIR/SHAKEN was never designed to be a complete fraud-detection or call-reputation system. Fraudsters can still exploit the ecosystem while using legitimate-looking caller IDs.

Why Call Attestation Doesn’t Stop Every Scam Contact

Call attestation ratings are intended to prove the legitimacy of calls. However, data from analyses of the call ecosystem don’t support these efforts. According to TNS’s 2026 Half-Year Robocall Investigation Report:

Approximately 85% of signed inter-carrier traffic among the largest U.S. communications service providers (CSPs) is signed.
Smaller/non-top-tier CSPs are much further behind, at around 20%.
Roughly 17% of confirmed spoofed calls carried an A-attestation.
About 1.6% of invalid numbers received an A-attestation.
Authentication can be present without legitimacy being guaranteed.

AI-generated voice cloning, SIM box fraud operations, and multimodal attacks all make scams more convincing and scalable with the tools available.

Authentication Doesn’t Tell You Whether a Call Is Wanted

A legitimate company can authenticate its outbound calls perfectly and still annoy consumers through excessive calling, poor practices, or high complaint rates.

Likewise, scammers may exploit weaknesses elsewhere in the telecommunications ecosystem while presenting seemingly trustworthy calls. Smaller companies may have vulnerabilities from legacy systems, malware, or outdated numbers that scammers can acquire.

AI Call Technology Compounds These Problems

Malwarebytes reports that AI is making robocalls more convincing, more scalable, and harder to detect. AI-generated voices can be created from small amounts of source audio. Scammers can combine voice cloning with spoofing and personal information.

Fraudsters don’t necessarily need to defeat STIR/SHAKEN itself. They can exploit weaknesses elsewhere in the call ecosystem, especially in legacy systems or global connectivity, where speed is prioritized over cryptographic verification.

The Unintended Reputation Problem With “Authenticated Calls”

Properly authenticated calls should instill consumer trust. However, if the consumer repeatedly receives spam and fraud calls from “authenticated” numbers, their trust in your ecosystem is diminished. This creates a fundamental problem for businesses whose legitimate customer interactions originate from unfamiliar numbers.

As spam calls increase, as noted in a CIDR data report, analytics engines can become more aggressive, leading to more flagged numbers among legitimate businesses.

The problem isn’t merely that scam calls get through, but that the sheer volume of unwanted calls makes consumers and carriers increasingly suspicious of legitimate calls, too. Although 2025 saw the lowest average number of caller ID flags per client, call flags spiked during certain events. They surged after the Federal Communications Commission (FCC) proposed a consent revocation rule in April 2025 and during a government shutdown when enforcement lapsed.

Disconnect Between Attestation Rating and Caller Reputation

While the attestation rating determines whether a call’s identity has been confirmed, the caller reputation determines whether the number can be trusted.

Ultimately, attestation establishes identity signals. Reputation establishes behavioral trust. Businesses need both. Each carrier and analytics engine uses unique technology and algorithms to determine how calls are delivered and displayed. The combination of attestation rating and caller reputation could lead to numbers being flagged or blocked by terminating service providers.

Call flagging has risen in carriers internally for inbound calls. Also, 50% of all call flags came from consumers marking their calls as spam, even if they are legitimate. This is another reason why call attestation must move beyond STIR/SHAKEN.

How Poor Caller Reputation Hurts Legitimate Businesses

Not only does poor caller reputation hurt customer interactions and operational costs, but it can also damage your brand’s reputation. Some factors that hurt your reputation include:

Lower answer rates with unknown or flagged numbers will see answer rates plummet.
More calls are going to voicemail, delaying outreach efforts, so messages are left for customers who don’t answer live calls.
Missed revenue opportunities due to lower answer rates, leading to fewer conversations and conversions.
Damaged customer experience with businesses relying on scheduling and updates misses opportunities with customers.
Increased operational costs from lower connection rates require increased operational costs and agent time.

Why Legitimate Businesses Can’t Simply “Get an A”

An A-level attestation rating doesn’t guarantee a successful call. A better approach combines call authentication with reputation management. Pairing these factors ensures your caller reputation rises in an ever-more distrustful customer ecosystem.

The New Model for Trusted Business Calling

Building a reliable, trusted calling model requires a multi-layered approach to enhancing your business calls.

Layer 1: Authentication – Work with trusted STIR/SHAKEN-compliant partners to strive for A-attestation ratings.
Layer 2: Reputation – Abide by compliant dialing regulations and ethical sales tactics to avoid customer complaints, flags, and blocks.
Layer 3: Analytics – Monitor your dialing behavior and analytics to ensure that call frequency, cadence, patterns, and anomalies don’t trigger flags or blocks on your numbers.
Layer 4: Caller Identity/Branding – Audit your caller ID display for consistency across networks and devices. If your logo appears differently through different carriers, it might cause confusion.
Layer 5: Continuous Monitoring – Actively monitor your phone number scores to determine changes in flagging behavior. A robust database and analytics engine solve this issue.
Layer 6: Remediate Negative Behavior – Swiftly remediate any erroneous or negative flags on your numbers to signify trust in the ecosystem.

Call attestation is a continuous cycle. This type of work never stops, and companies must keep the call list as clean as possible with the tools at their disposal, with these six layers creating reports at a regular cadence.

Monitor More Than Your Attestation Rating With Caller ID Reputation

While attestation ratings are important, they are but one cog in the machine that creates a trusted caller ID. Don’t let authentication create a false sense of security. Monitor your caller reputation, identify problems early, and take action before legitimate calls are blocked or labeled as spam.

Reach out to Caller ID Reputation for a consultation. We’ll help your team get on the right track to world-class call attestation.