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What is robocall mitigation?

Robocall mitigation is the set of practices and technologies carriers use to detect and block unwanted automated calls. The FCC requires every voice provider to file a Robocall Mitigation Plan documenting what they do. The combined effect is why your outbound calls might be labeled "Spam Likely" on the recipient's screen.

Definition

A robocall is any call that delivers a pre-recorded message or uses an autodialer. Most robocalls are legal (appointment reminders, school closures). A significant fraction are illegal (scams, telemarketing without consent). Mitigation tries to block the illegal ones without breaking the legal ones.

The layered defense

Modern robocall mitigation works in layers:

  1. Authentication. STIR/SHAKEN proves the calling number was signed by an originating carrier with attestation A, B, or C.
  2. Analytics. Terminating carriers run pattern analysis on call volume, call duration, complaint rates, and short-call ratios per source number.
  3. Reputation databases. Vendors (Hiya, First Orion, TNS) aggregate complaints across carriers and rate numbers in real time.
  4. Consumer apps. The native phone apps on iOS and Android query reputation databases at ring time and label calls before the screen lights up.
  5. Carrier blocking. Some carriers drop calls outright at the network level when reputation is bad enough.

How to stay trusted

Legitimate businesses can still get labeled "Spam Likely" if they call in ways that look robotic. Practices that hurt reputation:

  • High call volume from a single DID.
  • High ratio of short calls (under 10 seconds) suggesting hang-ups.
  • Calling lots of numbers that have never returned a call.
  • Aggressive retry on no-answer.
  • Mismatched caller ID name (CNAM) vs called brand.

Practices that help reputation:

  • Register the DID with carrier branded-call services (Verified Calls on Android, Number Branding via TNS).
  • Keep call volumes consistent. Burst patterns trigger flags.
  • Honor the National Do Not Call registry. See TCPA compliance.
  • Use multiple DIDs and rotate them when reputation degrades.

message.com tooling

Every call event in the Calls API includes a verificationResult field with the STIR/SHAKEN outcome. The Reports API exposes per-DID reputation metrics so customers can detect when a number is starting to be flagged and rotate before it gets worse.

Inbound calls flagged as likely-robocalls can be filtered automatically (sent to voicemail, dropped, or labeled in the queue). This is configured per phone number through PATCH /phone-numbers/:id.