Phone numbers
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, so calls can be routed to it.
How it works
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 LookValid products
| Product | Credits | Docs |
|---|---|---|
| Carrier Lookup (original carrier) | 1 credit per lookup (numbers outside the covered numbering plan areas are free) | API docs |
| Phone Intelligence (carrier and line status) | 1 credit per check (invalid numbers outside the US and Canada are free) | Product page |
New to the API? Start with the quickstart or the API reference. Agents can call the same lookups through the MCP server.