A method and apparatus for implementing international wireless roaming allows an international “roamer” to enter a visited system in a foreign country and originate calls. Upon entering the visited region, the roamer's mobile station initiates a registration request containing the mobile station's mobile identification number to the mobile switching center in the visited region. The mobile switching center initiates a message to an appropriate home location register. The home location register compares the mobile station's mobile identification number to a set of stored values. If an agreement is in place between the home location register provider and the roamer's home service provider, the home location register will return an appropriately formatted North American Numbering Plan mobile directory number to the mobile switching center. When the roamer initiates a call, the mobile switching center uses the mobile directory number in signaling call related information, specifically in populating parameters such as the Calling Pary Number. Recognizing a NANP-formatted number, the public switch telephone network will process the call as normal.