How to keep your AI voice agent number off spam lists: the 5-lever reputation strategy
A number flagged 'spam' by Hiya or Truecaller loses 60% of its answer rate in 48 hours. Here are the 5 levers to stay invisible to anti-spam algorithms and readable to your customers.
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Your number does everything right — clean opt-in, careful script, reasonable frequency — and suddenly answer rate drops from 55% to 22%. Likely cause: an anti-spam algorithm (Hiya, Truecaller, native Android app) just flagged you. Here are the 5 levers to stay visible. None are secrets — they're just systematically ignored.
Lever 1 — frequency and time window#
- No more than 1 call every 72h to the same destination number.
- Never before 9am or after 7pm in the recipient's local time.
- Never on Sunday (except life-emergency, signed off by a human).
- Daily outbound volume < 80% of your monthly baseline (otherwise = campaign signal).
Lever 2 — STIR/SHAKEN attestation A#
STIR/SHAKEN is the call-authentication standard used by US carriers and increasingly in Europe. Ask your SIP provider: 'Is my number signed at attestation A?'. Correct answer = yes, with proof. Vague answer = you're at attestation B/C, highly filterable. Change provider if necessary.
Lever 3 — branded calling (CNAM + logo)#
On recent iOS and Android, certain carriers display a name + logo instead of 'unknown number'. Registering with First Orion, Hiya Connect, or the Stir Shaken Registry costs $50-200/month — and triples answer rate. Mandatory for setups > 500 outbound calls/day.
Lever 4 — proactive reputation monitoring#
- Check weekly on Hiya, Truecaller, Spam Call Hunter, Whoscall whether your number is flagged.
- If flagged, open a ticket with the service (Hiya: hiya.com/business, Truecaller: truecaller.com/business).
- Unflag request: usually within 5 business days. Be ready to show opt-in compliance.
Lever 5 — warming up a new number#
Starting with a fresh number? Don't launch 200 calls on day one. Warm-up strategy: 20 calls on day 1 to your own CRM base (people who pick up and confirm), 40 on day 3, 80 on day 7. Over 14 days you build positive reputation before real volume. A cold number + 100 calls = banned in 48h.
The trap to absolutely avoid#
Buying a recycled number with inherited bad reputation. They sell cheaper but arrive already flagged. Check reputation before purchase on Truecaller: if the number has > 5 prior reports, refuse. Better to take a fresh number + warm-up.
The monthly test#
Once a month, call your own number from 5 different phones (Android, iPhone, with Truecaller, without, etc.). Note what shows up. If one shows 'suspected spam', you have 1 week to fix before the filter generalizes. First month VocazAI free to put this monitoring in place.