How to Get A-Level Attestation
A-level attestation is the single biggest authentication lever for answer rates — and you earn it indirectly through how your numbers and provider are set up. Here's how a brand qualifies.
You cannot ask for A-level attestation directly — there’s no form, no setting, and no fee that grants it. The originating provider assigns the grade based on how confident it is that you’re authorized to use the calling number. A means the provider authenticated you and confirmed the number is yours. So “getting A” is really about structuring your numbers and your provider relationship so the provider can confidently stamp A.
If you haven’t yet, read STIR/SHAKEN and attestation for what the grades mean. This page is the practical how-to.
How to qualify
- Use numbers your provider assigned or verifiedThe cleanest path to A is to originate from DIDs your provider gave you. The provider already knows it allocated those numbers to your account, so it can attest full authorization. If you bring your own numbers, your provider needs a way to verify you control them — ask whether it supports a number-verification or LOA (Letter of Authorization) process that upgrades BYO numbers to A.
- Avoid gateway and C-level trafficC (Gateway) attestation is effectively a spam red flag — it tells the terminating carrier the provider only knows where it received the call, not who originated it. Route your outbound calls directly through a provider that signs at origination, not through an international or interconnect gateway. If your calls are traversing a gateway and arriving as C, no amount of registration on the analytics side will fully recover the answer rate.
- Avoid B-level setups where you canB (Partial) is what you get when the provider authenticates you but can’t confirm you own the specific number — classic for an enterprise PBX or a BYOC SIP trunk using numbers from elsewhere. If you’re stuck at B, the fix is to consolidate: port the numbers to the signing provider, or use that provider’s number-verification process so it can move you to A.
- Confirm your provider is in the RMDA-level signing only helps if your provider’s traffic is accepted downstream. A provider that drops out of the Robocall Mitigation Database gets its traffic blocked by downstream carriers — your perfect attestation goes nowhere. Confirm your provider is filed and currently certified (see RMD).
- Verify what you're actually getting signed asAsk your provider to confirm, in writing, the attestation level it applies to your traffic. Some platforms expose it; others will tell you on request. Don’t assume A — verify it, because the difference between A and C is the difference between getting answered and getting labeled.
Quick diagnosis: which grade are you on?
| Your setup | Likely grade | What to do |
|---|---|---|
| Calling from DIDs your signing provider assigned you | A | You’re set — confirm and maintain RMD standing |
| BYO numbers, provider can’t verify ownership | B | Port numbers in, or use the provider’s number-verification process |
| Traffic traverses an international/interconnect gateway | C | Re-route to originate directly through a signing provider |
What A does — and doesn’t — buy you
A-level attestation gives you the best chance at clean delivery, but it is layer one of two. It does not, by itself, prevent a “Spam Likely” label: the analytics engines still score your dialing behavior independently. Think of A as necessary but not sufficient.
To turn A into actual answer rates, pair it with the rest of the program:
- Register every outbound number free at the Free Caller Registry.
- Keep your dialing hygiene clean (reasonable per-number volume, no spikes, clean lists).
- Set accurate CNAM as a baseline.
- Adopt branded calling (BCID/RCD) for the strongest lift.
Work through the full sequence with the outbound calling trust checklist.
Next: Spam-label remediation →