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 3.5 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.