Abstract: A telephone network includes switches which are capable of mapping between subscriber numbers, which are owned by the subscriber, and provider numbers, which define the physical location of the switch at which the subscriber is connected, in order to provide portability of telephone numbers. Switches which are capable of porting telephone numbers may access a database to look-up a provider number based on a subscriber number and look-up a subscriber number based on a provider number. The subscriber number of the called party is translated to a provider number in order to define the physical location of the switch supporting the called party. The provider number of the calling party is translated to a subscriber number to support caller ID. The database for maintaining information on translating subscriber numbers and provider numbers, and other data, such as call forwarding and switch configurations, may be accessed from a central database and cached locally to the switches.