Methodology
We use independent data sources, publish how much each signal counts, and guard against abuse.
Every lookup starts with the North American Numbering Plan. We reject numbers that can’t exist: area codes starting with 0 or 1, reserved N9X codes and the 555-01XX numbers used in fiction. We pick out toll-free, premium and Caribbean codes, and match the area code to its region, cities and time zone. Once NANPA/CNAC exchange data is imported, we also know the original carrier and rate center of every NPA-NXX block.
Live lookups through licensed providers such as Twilio and Telnyx return the current carrier, the line type (mobile, landline, fixed or non-fixed VoIP) and porting status. We cache results so the service stays fast and free.
Every weekday we sync the FTC’s Do Not Call “Reported Calls” data. Complaints are grouped by the number that placed the call, along with the robocall share and complaint topics.
People report what happened. Each report has a rating (unwanted, unsure or safe), a category with a severity weight, and optional details. Votes push helpful reports up, and flags hide abusive ones.
| Signal | Effect | Notes |
|---|---|---|
| Community reports | +0 … +55 | A report’s weight halves every 60 days. Safe ratings lower the score. |
| Report severity | −12 … +12 | Impersonation and bank fraud count more than surveys. |
| Report spike | +8 | 3 or more reports in 7 days, and at least double the week before. |
| FTC complaints | +0 … +30 | Logarithmic scale. Adds 5 more if most were robocalls. |
| Caribbean / premium code | +15 / +20 | Risk of one-ring scams and callback charges. |
| Line type | −3 … +8 | Non-fixed VoIP numbers are cheap and easy to throw away. Landlines are rarely used for mass dialing. |
| Impossible number | = 88 | A number that can’t exist on the network must have been spoofed. |
| Verified business | cap 15 | Ownership confirmed by our team. |
Verdicts: 0–24 likely safe, 25–49 use caution, 50–74 suspicious, 75–100 likely scam. A number with no signals at all shows “No reports yet”.