Phone validation: check if a number is real and active

Phone validation tells you whether a number is in service, what kind of line it is and how risky it looks, all in one lookup. Use it when a number arrives from a signup form, a lead list or a checkout and you need to decide what to do with it.

What it tells you

• What kind of line the number is, and whether it is currently active.
• The carrier behind the number, whether that carrier is a major one, and whether the number has been ported away from it.
• Basic location detail such as state and timezone.
• A fraud score and a risk level, with the risk signals behind them: SIM swap risk, a recently activated number, VoIP detection and how likely the number looks like a burner.
• A suggested next action, plus flags for whether SMS and voice are allowed and which channel to use for a one-time code.

What you need to provide

The phone number, with or without a country code. US and Canada numbers are normalized for you.

What it costs

1 credit per lookup. Live per-product costs are shown on the Billing page in your dashboard.

How to run it

• In the dashboard: Number Validation
• From your code: POST /v1/phone, then see the Developer Hub at app.1lookup.io/developer-hub.

Good to know

• Results are point-in-time. A number that is active today can be disconnected, ported or reassigned later, so re-check numbers you keep on file.
• This is the broad one-call check. If the line type is all you need, Number Type Detection is the narrower lookup, and HLR Status Check is the one that says whether the handset is switched on right now.
• The score and the recommended action are inputs to your decision, not a verdict. You set the thresholds for what you accept, review or reject.
• A phone number can identify a person, so what comes back is personal data. Use it for legitimate business purposes only.

Updated on: 24/08/2026