Abstract: A centralized database connected to the next to last Service Switching Point (SSP) within a Public Switched Telephone Network (PSTN) interfacing with a ported Public Land Mobile Network (PLMN) stores correlation data correlating a network address representing the new home location register (HLR) associated with a ported mobile station with a mobile identification number representing that particular mobile station. Whenever an incoming signal such as an Initial Address Message (IAM) is received by the next to last SSP, a database query is performed towards the centralized database to retrieve the network address representing the new HLR. The retrieved HLR network address is then utilized as the Called Party Address (CdPn). The original mobile station number is also included into the Generic Address Parameter (GAP) of the routed IAM signal.