--- title: "STIR/SHAKEN Attestation A, B, C for AI Outbound Voice in 2026" description: "What attestation level your AI calls actually receive, why Level A is the only one that lights up Caller Verified on the receiver's screen, and how to get there with a Twilio-style trust profile." canonical: https://callsphere.ai/blog/vw2d-stir-shaken-attestation-ai-outbound-2026 category: "AI Infrastructure" tags: ["STIR/SHAKEN", "Attestation", "Caller ID", "FCC", "Twilio"] author: "CallSphere Team" published: 2026-03-18T00:00:00.000Z updated: 2026-05-07T09:32:11.156Z --- # STIR/SHAKEN Attestation A, B, C for AI Outbound Voice in 2026 > What attestation level your AI calls actually receive, why Level A is the only one that lights up Caller Verified on the receiver's screen, and how to get there with a Twilio-style trust profile. > An AI outbound call signed at Level A reads "Caller Verified" on supported handsets. The same call signed at Level C reads as a possible spam call on most carriers. The difference is whether your originating provider can vouch for both you and the number on the From header. ## What the rule says ```mermaid flowchart TD Out[Outbound campaign] --> Twilio[Twilio Voice API] Twilio --> STIR[STIR/SHAKEN attestation] STIR --> Carrier[Originating carrier] Carrier --> Term[Terminating carrier] Term --> Recipient[Recipient phone] Recipient --> Webhook[/voice webhook/] Webhook --> Agent[AI sales agent] ``` CallSphere reference architecture STIR/SHAKEN is a pair of standards (STIR for the cryptographic identity passport, SHAKEN for the carrier framework) that the FCC mandated for IP-based originations starting June 30, 2021, with extension deadlines closed for nearly all carriers by mid-2025. Each call carries a SIP Identity header signed by the originating provider, asserting one of three attestation levels: A (Full) when the provider knows the customer and verifies the right to use the From number, B (Partial) when the provider knows the customer but cannot verify the number, and C (Gateway) when the provider only sees the call entering its network from elsewhere. The FCC's December 2025 update tightened reporting; carriers now file attestation statistics quarterly and small-carrier exemptions have largely been eliminated. ## What it means for AI voice agent operators For AI outbound, attestation level is essentially answer-rate. CTIA-aligned analytics partners (TransUnion, First Orion, Hiya) take attestation as a major signal in spam scoring. Calls signed C trend toward "Spam Likely" labels in days; calls signed A retain neutral or positive labels. To earn Level A on your AI outbound, your originating carrier must (1) have a verified business identity for you and (2) confirm that the From number you assert is a number you control. The cleanest path is buying numbers from the same carrier you originate with and registering them inside that carrier's trust product. Bring-your-own numbers ported in get there too, but the carrier needs ownership records. For AI in particular, FCC has clarified that AI-generated voices are "artificial" under the TCPA. STIR/SHAKEN does not exempt you from TCPA consent. A call can be Level A signed and still illegal if you lack consent. Attestation is about who you are, not whether the call should happen. ## How CallSphere stays compliant Every CallSphere outbound call rides Twilio Programmable Voice with a Customer Profile in Twilio Trust Hub plus a SHAKEN/STIR Trust Product attached. Numbers we provision through Twilio are bound to that profile, so calls sign Level A by default. Sales Calling AI runs five concurrent outbound calls per tenant on Twilio with TCPA opt-out flows recorded inline. After-Hours AI fires per-contact outbound calls plus SMS to on-call staff with a 120-second timeout. Healthcare AI is HIPAA and SOC 2 aligned; the same trust profile signs its outbound confirmations. Where customers want to bring their own numbers, we walk them through Twilio's hosted-number SHAKEN/STIR onboarding so attestation does not silently downgrade. ## Compliance checklist 1. Choose an originating carrier that supports A-level signing on your numbers (Twilio, Telnyx, Bandwidth, Plivo all do). 2. Complete the carrier's Customer Profile / Trust Hub vetting (legal name, EIN, website, business address). 3. Attach a SHAKEN/STIR Trust Product to the profile and bind every outbound number to it. 4. For ported-in numbers, supply ownership documentation so the carrier can sign A. 5. Monitor attestation in your CDR; alert when sustained A-rate drops below 95%. 6. Register branded calling (CNAM and rich call data) for an additional trust uplift. 7. Keep Caller ID consistent: rotating or random From numbers tank trust scores even at Level A. 8. Honor the FCC's "consent + identification + opt-out" trio for any AI-prerecorded or AI-generated voice call. 9. Implement TRACED Act robocall mitigation database (RMD) entries if you are a downstream provider. 10. Review TransUnion/Hiya/First Orion analytics weekly; appeal mislabels through your carrier. ## FAQ **Will Level A guarantee my AI call rings through cleanly?** No. It is a strong signal, not a free pass. Behavior matters too: short calls, low pickup rates, and complaint rates still drag your reputation down. **Does STIR/SHAKEN apply to international calls?** STIR/SHAKEN is US-centric. Cross-border calls land at the receiving country's edge with a Level C if no peering trust exists. Canadian carriers run their own SHAKEN deployment under CRTC oversight. **Can my AI agent spoof a different From number for a callback?** Only if you control or are authorized to use that number. Using a number you do not own degrades to B or C and may violate the TRACED Act regardless. **What if my originating carrier signs C on my numbers?** That usually means the trust product or number assignment is misconfigured. Open a ticket; the fix is paperwork, not infrastructure. **Does Branded Calling fix bad reputation faster?** It speeds up the recovery curve once your behavior is clean, but it does not paper over real complaints. ## Sources - [FCC: STIR/SHAKEN Robocall Mitigation](https://www.fcc.gov/call-authentication) - [Twilio: Trusted Calling with SHAKEN/STIR](https://www.twilio.com/docs/voice/trusted-calling-with-shakenstir) - [TransUnion: STIR/SHAKEN Attestation Levels](https://www.transunion.com/blog/what-are-the-attestation-levels-for-stir-shaken) Start a [14-day trial](/trial) with Level A signing on Day 1, browse [pricing](/pricing), or [contact us](/contact) for trust-product help. --- Source: https://callsphere.ai/blog/vw2d-stir-shaken-attestation-ai-outbound-2026