| In the U.S., a Location Routing Number (LRN) is a 10-digit number in a database called a Service Control Point (SCP) that identifies a switching port for a local telephone exchange. LRN is a technique for providing Local Number Portability (LNP). Using LRN, when a phone number is dialed, the local telephone exchange queries a routing database, usually the SCP, for the LRN associated with the subscriber. The LRN removes the need for the public telephone number to identify the local exchange carrier. If a subscriber changes to another telephone service provider, the current telephone number can be retained. Only the LRN needs to be changed. |
| In addition to supporting service provider phone number portability, an LRN also supports the possibility of two other types of number portability: service portability (for example, ordinary service to ISDN) and geographic portability. |
| LRN is an alternative to the current NPA-NXX format described in the North American Telephone Numbering System (NATNS). |
| LNPs and LRNs are supervised by the Number Portability Administration Center, operated by Lockheed Martin under the appointment of the Federal Communications Commission (FCC). |