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# Ported number check: find the carrier a number moved to

A portability (MNP) lookup tells you whether a phone number has been moved to a different carrier, and which carrier holds it now. Use it when routing messages or calls, or when your records still show the carrier a number started on.

## What it tells you

- Whether the number has been ported away from the carrier it was issued by.
- The carrier the number sits on today.
- The carrier the number originally belonged to.
- A suggested next action based on the result.

## What you need to provide

The phone number you want to check. International format (E.164) is strongly recommended.

## What it costs

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

## How to run it

- In the dashboard: Carrier Portability (MNP)
- From your code: POST /v1/mnp-lookup, then see the Developer Hub at app.1lookup.io/developer-hub.

## Good to know

- Results are point-in-time. People port numbers whenever they switch providers, so a result from last quarter can already be out of date.
- Routing rules built on the number range alone go wrong once a number is ported. This lookup is what tells you the difference.
- A number that has not been ported still returns the carrier detail, so you can use it either way.
- Number Validation reports ported or not ported as part of its broader check. Use this lookup when you also need the carrier the number came from.