STIR/SHAKEN Attestation A: Stop 'Scam Likely' Labels Forever

Full attestation with cryptographic call authentication—your calls reach customers, not spam folders

Last Updated: February 2026

What is STIR/SHAKEN?

STIR/SHAKEN stands for Secure Telephone Identity Revisited (STIR) and Signature-based Handling of Asserted information using toKENs (SHAKEN). It's a framework for authenticating caller ID information to prevent spoofing and reduce robocalls.

In 2019, Congress passed the TRACED Act, requiring all carriers to implement STIR/SHAKEN by June 30, 2021. This system uses digital certificates to cryptographically sign calls, proving the caller is who they claim to be.

Key Fact: 87% of Americans don't answer calls from unknown numbers. STIR/SHAKEN Attestation A ensures your legitimate business calls aren't flagged as "Scam Likely" or "Spam Risk."

The 'Scam Likely' Problem

Carriers and third-party analytics engines (First Orion, TNS, Hiya) flag millions of calls daily as potential spam. While this protects consumers, legitimate businesses suffer:

Without STIR/SHAKEN

  • Calls labeled "Scam Likely" or "Spam Risk"
  • 87% of calls go unanswered
  • Lost revenue from missed connections
  • Damaged brand reputation
  • Customers assume you're a scammer
  • Carrier blocks without warning

With Attestation A

  • Verified caller ID display
  • 85%+ answer rate for known businesses
  • Protected from false spam flags
  • Enhanced brand trust
  • Carrier preferential routing
  • TRACED Act compliant

Real Cost: A single "Scam Likely" label can cost you a customer forever. They won't answer, won't call back, and will tell others your business number is spam.

The Three Attestation Levels

STIR/SHAKEN has three attestation levels. Only Attestation A provides full protection:

Attestation A (Full) - What Callbetter Provides

The originating carrier authenticates both the caller's identity and their right to use the phone number. This is the highest trust level.

Requirements:

  • Direct carrier relationship (not resold numbers)
  • Phone number ownership verified with number portability database
  • Know Your Customer (KYC) verification of business identity
  • Certificate authority integration for call signing

Benefits:

  • Highest trust score with carriers and analytics engines
  • Lowest probability of spam labeling (<1% false positive rate)
  • Customer devices may show verified check mark or business name
  • Preferential routing during network congestion

Attestation B (Partial)

Carrier authenticated the caller's identity but cannot verify they have the right to use the specific phone number being displayed. Often used for ported numbers or enterprise PBX systems.

Risk: Lower trust score increases chance of spam labeling, especially with high call volumes.

Attestation C (Gateway)

Carrier can authenticate neither the caller nor the phone number. Often assigned to international calls, certain VoIP providers, or gray routes.

Risk: High probability of spam labels. Many carriers automatically block Attestation C calls.

How Callbetter Achieves Attestation A

Unlike many VoIP providers stuck at Attestation B or C, Callbetter maintains the infrastructure required for full Attestation A:

Direct Carrier Relationships: Callbetter operates as a facilities-based carrier, not a reseller. This gives us the authority to attest to both caller identity and number ownership.
Certificate Authority Integration: We maintain direct integration with STIR/SHAKEN certificate authorities, allowing us to cryptographically sign every outbound call in real-time.
Know Your Customer (KYC) Verification: Every Callbetter customer completes identity verification. This validates we know who is making calls and prevents number hijacking. See Terms of Service Section 5.5.
Continuous Monitoring and Re-validation: Attestation status is monitored per-call. If certificates expire or validation fails, we alert you immediately and prevent non-compliant calls.

TRACED Act Compliance

The Telephone Robocall Abuse Criminal Enforcement and Deterrence (TRACED) Act of 2019 mandates STIR/SHAKEN implementation and establishes strict penalties for non-compliance:

Legal Requirements for Carriers and VoIP Providers:

  • Implement STIR/SHAKEN authentication on all IP-based networks
  • Block calls with invalid or missing authentication (as of June 2023)
  • Trace back origins of illegal robocalls within 24 hours
  • Maintain call detail records for regulatory investigations
  • Participate in industry traceback consortium (US Telecom's ITG)

No Caller ID Spoofing (47 U.S.C. § 227(e)):

It is illegal to transmit misleading or inaccurate caller ID information with intent to defraud, cause harm, or wrongfully obtain anything of value. Penalties include $10,000 per violation and potential criminal charges.

See our Acceptable Use Policy Section 6.3 for complete anti-spoofing requirements.

How Callbetter Ensures Compliance:

  • Automatic STIR/SHAKEN signing on all outbound calls
  • Caller ID must match registered business phone numbers
  • Prevents spoofing through number ownership verification
  • Real-time call analytics to detect fraud patterns
  • Immediate suspension for robocalling or spoofing violations

Beyond STIR/SHAKEN: Call Reputation Management

STIR/SHAKEN authentication is necessary but not sufficient. Carriers and analytics engines also evaluate your calling behavior:

Reputation Factors Tracked:

  • Answer rates: Do people pick up your calls?
  • Call duration: Scam calls hang up quickly; legitimate calls last minutes
  • Complaint rates: How many people mark you as spam?
  • Block rates: How often are you blocked by consumers?
  • Calling patterns: Sequential dialing and high volume trigger flags
  • Time of day: Calling at odd hours decreases trust

Analytics Engines:

  • First Orion (T-Mobile): Powers "Scam Likely" labels
  • TNS (AT&T): Call Protect and spam warnings
  • Hiya (Samsung, AT&T): Caller ID and spam detection
  • Truecaller: Crowdsourced spam database
  • Nomorobo: Robocall blocking service

Callbetter monitors your reputation scores across major analytics engines and alerts you to degradation before it results in spam labels.

SIP 603+ Transparency: When Calls Get Blocked

As of March 25, 2026, carriers must return a SIP 603+ response code when blocking calls as "Network Blocked." This transparency requirement helps legitimate businesses identify and remediate false positives.

How Callbetter Surfaces This: When a call is blocked, you'll see "Network Blocked" in your call logs with details about which carrier blocked it. We provide remediation guidance and can escalate to carrier relationships.

Remediation Process:

  1. Identify the blocking carrier from call detail records
  2. Review reputation scores from analytics engines to understand the trigger
  3. Submit whitelist request through carrier portal (Callbetter can assist)
  4. Provide evidence of legitimate business use, including customer relationships
  5. Adjust calling behavior if patterns triggered false flag

See our Acceptable Use Policy Section 6.2 for details on SIP 603+ handling. You remain responsible for resolving carrier disputes.

How to Avoid 'Spam Likely' and 'Scam Risk' Labels

Even with Attestation A, poor calling practices can damage your reputation. Follow these best practices:

Caller ID Configuration:

  • Always display your registered business phone number
  • Never spoof caller ID to show local area codes (this is illegal)
  • Use consistent caller ID—switching numbers frequently looks suspicious
  • Register your business name with CNAM (Caller Name) databases

Call Frequency and Timing:

  • Limit outbound calls to business hours (9 AM - 8 PM local time)
  • Avoid calling the same number repeatedly in short periods
  • Space calls to different numbers to avoid "burst" patterns
  • Don't use predictive dialers or sequential number generators

Handling Customer Complaints:

  • Maintain internal Do Not Call list and honor requests immediately
  • Keep complaint rates below 1% (industry standard for clean reputation)
  • If someone marks you as spam, investigate why and adjust approach
  • Never call numbers that have blocked you or marked you as spam

Call Quality and Professionalism:

  • Engage professionally—long calls signal legitimate business
  • Leave voicemails that clearly identify your business and purpose
  • Train staff on compliance—aggressive tactics damage reputation
  • Monitor call recordings for quality assurance (with consent)

What Breaks STIR/SHAKEN Attestation

Even legitimate businesses can lose Attestation A. These actions will downgrade or break your attestation:

Number porting without proper verification: If you port a number from another carrier without completing KYC re-verification, attestation may drop to B or C.
Spoofed or unregistered caller IDs: Displaying a number you don't own breaks attestation and violates TRACED Act.
Unverified business information: Providing false business details during KYC can result in certificate revocation.
Traffic pumping and fraud patterns: Suspicious call patterns can trigger carrier investigations and attestation suspension.
Using competitor/benchmarking services illegally: Per Terms of Service Section 5.4, using Callbetter for competitor analysis can result in service termination.

The Callbetter Advantage

STIR/SHAKEN compliance isn't a one-time setup—it requires ongoing infrastructure and monitoring:

Built-in KYC Verification: Every customer completes identity verification during onboarding. This is required for Attestation A and prevents number hijacking.
Automatic STIR/SHAKEN Signing: Every outbound call is cryptographically signed with Attestation A. No configuration required—it just works.
Real-Time Attestation Monitoring: Dashboard shows attestation level per-call. Certificate expiration and validation failures trigger immediate alerts.
Reputation Score Tracking: Monitor your reputation across First Orion, TNS, Hiya, and other analytics engines. Proactive alerts help prevent spam labels.
Remediation Support: If your calls are incorrectly flagged, our support team helps navigate carrier whitelist processes and dispute resolution.
Integrated Compliance Framework: STIR/SHAKEN works alongside A2P 10DLC, Terms of Service, and Acceptable Use Policy for comprehensive compliance.

Technical Implementation Details

For technical users interested in how STIR/SHAKEN works under the hood:

Certificate Chain Validation:

Calls are signed using X.509 certificates issued by authorized STI-CAs (STIR/SHAKEN Trusted Authorities). Certificates contain the Service Provider Code (SPC) token proving carrier authority. Receiving carriers validate the certificate chain back to the root CA.

PASSporT Token Structure:

Each call includes a PASSporT (Personal Assertion Token) containing:

  • Origination number: The calling party's phone number
  • Destination number: The called party's phone number
  • Attestation level: A, B, or C
  • Timestamp: When the call was originated
  • Digital signature: Cryptographic proof of authenticity

SIP Identity Header:

The signed PASSporT is transmitted in the SIP Identity header of the INVITE message. Format: Identity: <PASSporT>;info=<certificate URL>;alg=ES256

Verification Process Flow:

  1. Originating carrier signs call with private key
  2. PASSporT token and certificate URL included in SIP INVITE
  3. Intermediate carriers pass through Identity header unchanged
  4. Terminating carrier retrieves certificate from published URL
  5. Terminating carrier validates signature using public key
  6. If validation succeeds, call is marked with attestation level
  7. Consumer devices or analytics engines display appropriate trust indicators

Stop 'Scam Likely' Labels—Get Attestation A Today

Join thousands of businesses that trust Callbetter for STIR/SHAKEN Attestation A and full TRACED Act compliance. Your calls will reach customers, not spam folders.

Start Your Free TrialContact Our Team

Questions about STIR/SHAKEN? Email support@callbetter.com or view our Terms of Service, Acceptable Use Policy, and A2P 10DLC Compliance pages.