What makes a good spam call blocking API?

Three things: freshness, evidence and latency. Spammers rotate numbers within hours, so a blacklist refreshed every minute beats one refreshed daily. Evidence means complaint history you can audit instead of a bare score. And the response has to arrive fast enough to act during call setup.

Does it block robocalls too?

Yes. Complaint records carry a RecordedMessageOrRobocall flag, so robocall campaigns surface in the data the moment consumers start reporting them, and the number lands on the blocklist.

Where does the blocking actually happen?

Wherever you want it. Call the API per call and drop based on the response, host the spam feed at your switch or SBC for zero-latency blocking, or ship the white-label SDK and block on the device itself.

Can it handle enterprise call volumes?

Yes. Volume plans scale from roughly 300,000 to 50,000,000+ lookups per month, and the self-hosted feed removes per-call lookups entirely for carrier-scale traffic. White-label terms are available for resellers.

Spam call blocking API with evidence behind every verdict

A spam call blocking API for CPaaS, UCaaS and telecom. One request returns the verdict and the proof, refreshed every minute. Block at the API, the switch or the device, and sell the protection under your brand.

Get an API key Talk to sales

terminal

$ curl -H "x-auth: $API_KEY" \
    https://callerapi.com/api/lookup/+18882211161

{
  "reputation": "SPAM",
  "is_spam": true,
  "spam_score": 100,
  "total_complaints": 43,
  "complaints": [{
    "Subject": "Calls pretending to be government",
    "RecordedMessageOrRobocall": "Y",
    "ConsumerState": "Missouri"
  }]
}

From ring to response in one round trip

No machine learning pipeline to babysit. The complaint data already knows the number.

Call hits your edge

Your switch, SBC, dialer or app fires a lookup while the call is still setting up.
Response comes back

Spam score, reputation and complaint evidence from data refreshed every 60 seconds across 30 countries.
You decide the action

Drop it, label it, or send it to voicemail. Your policy, enforced with evidence you can show subscribers.

Pick where the block happens

Same spam intelligence, three enforcement points. Most customers start with the API and add the feed as volume grows.

Deployment	Best for	Lookup latency	Where it runs
Blocking API	CPaaS, UCaaS, dialers, apps	One round trip per call	Our cloud
Spam phone number database	Carriers, MVNOs, high volume, flat fee	Zero, list is local	Your switch or SBC
Call blocking SDK	Mobile apps, white-label, anonymous lookups	Zero, on-device	Subscriber's phone

Running a network? The feed and SIP firewall are covered in depth under telecom fraud prevention.

Sell the protection. Keep the margin.

CPaaS and UCaaS platforms do not buy this API to save minutes. They buy it to sell a protection tier: spam labels and blocking on every line, billed monthly, under their brand. Volume plans run from about 300,000 to 50,000,000+ lookups a month, and screening logic can run before an AI or human agent ever answers. Numbers that are flagged as spam on your own side? Check them with the DID reputation monitoring API.

Scope a volume deal

Spam call blocking API questions

Block the next robocall wave

Grab a key and make your first lookup in minutes, or bring us your volumes for a custom quote.