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).