LRN (Location Routing Number) In the United States, a 10-digit number that identifies a switch port for a central office (CO), an LRN is used to provide local number portability (LNP). The LRN is maintained in a Services Management System (SMS) database in a Service Control Point (SCP), which is 74570c12.qxd 9/11/07 12:25 PM Page 297 |