Twilio SHAKEN/STIR Registration: Step-by-Step Guide for AI Calling Campaigns

Why your answer rate is probably lower than it should be

You've built a great AI calling agent. Clear script, good voice, fast response times. But your answer rate is 25%, and industry benchmarks suggest you should be seeing 40%+.

The problem usually isn't your agent. It's that your phone numbers are showing up as "Spam Likely" or "Unknown" on the recipient's caller ID — and in 2026, most people don't answer either.

Three compliance systems determine whether your number displays as legitimate:

1. SHAKEN/STIR — Call attestation protocol that validates the caller's identity
2. CNAM — The database that shows your business name instead of just a number
3. A2P 10DLC — Application-to-Person registration required for high-volume outbound calling

Skip any of these and you're actively fighting your own answer rate.

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What each system does

SHAKEN/STIR

SHAKEN/STIR (Signature-based Handling of Asserted Information Using toKENs / Secure Telephone Identity Revisited) is the FCC-mandated caller ID authentication standard.

When you make a call, your carrier attaches an attestation level to the call:

• A (Full): Carrier has verified the caller owns the number
• B (Partial): Caller is known but number ownership isn't confirmed
• C (Gateway): Carrier only knows the call came through their network

Carriers on the receiving end (Verizon, T-Mobile, AT&T) use this attestation to decide whether to:

• Display the number normally
• Display "Spam Likely"
• Block the call entirely

Unsigned calls or C-level attestations are increasingly being blocked outright.

CNAM

CNAM (Caller Name) is the database that tells the recipient's carrier what name to display for your number. Without CNAM registration, your number shows as "Wireless Caller," "Unknown," or just the number itself.

With CNAM registered, it displays your business name — instantly signaling legitimacy.

A2P 10DLC

A2P 10DLC is a registration system for commercial SMS and voice over 10-digit long codes (i.e., regular US phone numbers). The major carriers enforce this — unregistered traffic gets throttled or blocked.

Even if you only do voice calling, A2P registration improves how your numbers are treated by carriers.

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Step 1: A2P 10DLC Brand Registration

This is the foundational step. Every other registration depends on it.

In Twilio Console:

1. Go to Messaging → Regulatory Compliance → A2P 10DLC
2. Click "Register Brand"
3. Fill in your business info:
   • Legal business name (must match your EIN records exactly)
   • EIN (Employer Identification Number)
   • Website
   • Business address
   • Primary contact email and phone
4. Submit for verification

Cost: $4 one-time registration fee + $44 vetting fee (recommended, improves throughput limits).

Timeline: 1–3 business days for approval.

Common rejection reasons:

• Business name doesn't match EIN records
• Website doesn't clearly indicate what the business does
• Address discrepancy between registration and public records

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Step 2: A2P 10DLC Campaign Registration

After Brand approval, register each campaign (use case) for which you'll send messages or calls.

Campaign types:

• Low Volume Mixed (best for most small businesses)
• Account Notifications
• Marketing (more scrutiny, needs explicit opt-in documentation)
• Customer Care
• Agents & Franchises (for multi-location businesses)

What you need:

• Campaign description (1–2 sentences)
• Sample messages / call scripts that will be sent
• Opt-in method documentation (how leads consented to receive calls/texts)
• Privacy policy URL
• Terms of service URL

Cost: $10/month per campaign.

Timeline: Usually approved within 24 hours for standard campaigns; up to a week for Marketing campaigns.

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Step 3: Acquire and Register Phone Numbers

Purchase numbers through Twilio Console → Phone Numbers → Manage → Buy a number.

For AI calling campaigns, choose:

• Local numbers matching the area code of your target market (higher answer rates than toll-free)
• Capability: Voice + SMS (even if only using voice — full capability allows for future text follow-up)
• Multiple numbers — one number per 50 calls/day maximum to avoid spam flagging

After purchase, register each number to your campaign:

1. Go to the number's Configuration page
2. Scroll to Messaging Configuration
3. Assign to your registered A2P 10DLC campaign
4. Save

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Step 4: SHAKEN/STIR Configuration

Twilio automatically signs SHAKEN/STIR attestations for calls from your numbers — but only if the number is registered correctly.

How to verify your attestation level:

1. Make a test call to yourself (or a colleague on a different carrier)
2. Check your caller ID display — if it shows "Verified" or a green checkmark, you're at attestation level A
3. If it shows plain number or "Spam Risk," attestation is lower

To improve attestation:

• Ensure A2P 10DLC Brand is approved (this alone gets you A-level for campaign-registered traffic)
• Register your business phone number through Twilio's Branded Calling feature
• Verify your outbound caller ID matches the number actually being displayed

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Step 5: CNAM Registration

Option A — Twilio Branded Calling: Twilio offers a branded calling feature that works across Verizon, T-Mobile, and AT&T. Costs approximately $15/month per number. Displays your logo + business name + call reason on the recipient's phone.

Option B — Traditional CNAM: Register with CNAM providers like TransUnion or Neustar directly. Takes 2–4 weeks to propagate across all carriers. Costs around $5/month per number for database entry.

Option C — Twilio Caller ID Registration: Basic option. Costs $1/month per number. Registers your number for business display. Less rich than Branded Calling but better than nothing.

For AI calling campaigns at scale, Option A (Branded Calling) delivers the biggest answer-rate improvement.

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The compliance checklist

Before running a volume AI calling campaign, verify:

• [ ] A2P 10DLC Brand registered and approved
• [ ] A2P 10DLC Campaign registered for your use case
• [ ] Phone numbers purchased from Twilio (local to target market)
• [ ] Phone numbers assigned to the registered campaign
• [ ] Test call shows "Verified" or attestation A on your caller ID
• [ ] CNAM or Branded Calling configured for displayed business name
• [ ] At least 3–4 phone numbers in rotation per 100 calls/day
• [ ] Call velocity limited to 50 calls/hour per number
• [ ] Opt-in documentation archived (proves consent for TCPA)

Skipping any of these is like shipping a product without testing it on the recipient's device. The call lands but the experience is broken.

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Real-world impact

From Twilio's own published data on SHAKEN/STIR effectiveness:

• Calls with A-level attestation have 3–5x higher answer rates than unattested calls on participating networks
• Branded Calling features (displaying business name) have been shown to increase answer rates 20–40% in Twilio's case studies

These numbers aren't marketing claims — they're consistent with what most AI calling operators see after implementing proper registration.

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What if you're not using Twilio?

Other major providers (Bandwidth, Plivo, Vonage) have equivalent registration flows. The systems (A2P 10DLC, SHAKEN/STIR, CNAM) are carrier-mandated — every provider has to support them.

The steps above are Twilio-specific. For other providers, search their documentation for "A2P 10DLC registration" and "SHAKEN/STIR."

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Sources

Procedures are based on Twilio's official documentation as of April 2026 (see twilio.com/docs/messaging/compliance and twilio.com/docs/voice/shaken-stir). Pricing varies by region and volume — verify on Twilio's pricing pages before committing.

Need help running through the full registration checklist? Get in touch — I've done this dance for 13+ client deployments.