A method reduces the number of queries generated to a number portability database. The number portable communication system includes a local cache associated with the switching office or facility responsible for identifying and controlling the routing of calls to portable numbers. By including the cache and only generating a request to the number portability database when the cache either does not contain LRN response information or if a call attempted based on LRN response information in the cache fails, the total number of queries to the number portability database are reduced. This reduces query traffic as well as speeds up the processing of calls able to use cached information.