How a case file is built

1. Normalize and validate

We read the number in any common format, convert it to the international standard (E.164), and check it against the official numbering plan for its country. Invalid numbers stop here before any outside lookup runs.

2. Numbering facts

Country, calling code, and — for North American numbers — the area code's assigned state or province. This tells you where a number was issued, not where the caller is.

3. Federal records

For North American numbers we search the FCC's public consumer complaint data for unwanted calls that list this number as the caller ID or advertiser number. Results are cached for several hours so repeat searches are fast.

4. Risk classification

We sort numbers into Low concern, Some caution, or Elevated number-risk signals, based on complaint count, robocall reports, and how recent they are. Every case file lists exactly why.

5. What's labeled how

• Numbering plan / NANPA — reference facts about the number range.
• Public record — government-published consumer complaints.
• Inference — our own conclusions, like time zone or risk level.
• Community — visitor reports (not active yet).

Details on each source are on the sources page.