---
title: "What is LRN (Location Routing Number)?"
url: "https://lookvalid.com/glossary/lrn.md"
canonical_url: "https://lookvalid.com/glossary/lrn"
last_updated: "2026-10-17"
type: "conceptual"
summary: "In North America, a Location Routing Number is a ten-digit number that identifies the switch currently serving a ported phone number."
related: ["https://lookvalid.com/glossary/number-portability.md", "https://lookvalid.com/glossary/carrier-lookup.md", "https://lookvalid.com/glossary/nanp.md", "https://lookvalid.com/products/carrier-lookup.md"]
---

# What is LRN (Location Routing Number)?

In North America, a Location Routing Number is a ten-digit number that identifies the switch currently serving a ported phone number.

In North America, a Location Routing Number is a ten-digit number that identifies the switch currently serving a ported phone number, so calls can be routed to it.

When a number moves between carriers, the networks keep a record that maps the old number to the new carrier's switch. The LRN is that switch identifier. Looking it up is the standard way to find the carrier that holds a ported number today.

LRN data is built for call routing, and some data suppliers restrict how it can be reused, which affects whether it can be sold on as a lookup product.

## Related

- [What is Number portability?](https://lookvalid.com/glossary/number-portability.md)
- [What is Carrier lookup?](https://lookvalid.com/glossary/carrier-lookup.md)
- [What is NANP (North American Numbering Plan)?](https://lookvalid.com/glossary/nanp.md)
- [Carrier Lookup (original carrier) API](https://lookvalid.com/products/carrier-lookup.md)