Phone Number Validator
Validate any US or Canada phone number against the North American Numbering Plan (NANP) format rules. Free, instant, no signup.
Validates format only — does not check whether the number is currently in service. For carrier and current assignment info, use our reverse lookup tool.
How NANP phone number validation works
Every phone number in the North American Numbering Plan (NANP) follows a strict 10-digit format: (NPA) NXX-XXXX. The validator checks each component against the official NANP numbering rules:
- NPA (area code): 3 digits. First digit must be 2–9, middle digit must be 0–8, last digit can be 0–9. Total ~400 valid combinations.
- NXX (central office prefix): 3 digits. Same rules as NPA — first digit 2–9, middle digit 0–8, last digit 0–9.
- XXXX (subscriber line): 4 digits, any value 0000–9999.
If any of these checks fail, the number is structurally invalid and could never have been assigned by NANPA. Note that this validator only checks format — it does not query whether the number is actually in service. For that, you need a real-time HLR (Home Location Register) lookup from a carrier-grade API.
Why use a phone validator?
Validating phone numbers before you call or text them is essential for:
- Lead capture forms: Reject obviously fake numbers like (555) 555-5555 at the form level.
- SMS campaigns: Avoid wasting SMS API credits on invalid numbers.
- CRM cleanup: Detect and remove malformed entries from customer databases.
- Fraud prevention: Flag numbers that don't match the expected area code format.