Nomorobo utilizes a MASSIVE database of known, illegal robocallers, that we've compiled with the help of the FTC, user reports, and our own honey traps. The blocklist contains over 5 Million robocallers and grows every single day.
If a call gets a match in our database, we grab the call. If there's no match, we let the call go through.
We also maintain a growing allowlist of numbers we will never block.