Patent ID: 7203496

Claim:
A method of relating a directory number to a mobile station in a wireless network for an incoming call from a calling party using a calling party device to a called party using the mobile station, wherein the directory number is associated with a first mobile switching center and wireless service to the mobile station is associated with a second mobile switching center, the method including the steps: a) the first mobile switching center querying a local number portability data storage device, in lieu of querying an external number portability database, for stored routing information associated with the directory number and time information associated with a date and time when a previous number portability query associated with the directory number returned the stored routing information; b) receiving a return result from the local number portability data storage device; c) determining if the return result from the local number portability data storage device includes the stored routing information; d) determining if the stored routing information is expired by determining if the time information associated with the stored routing information exceeds a first predetermined time threshold; e) if the return result from the local number portability data storage device includes the stored routing information and if the stored routing information is not expired, forwarding the incoming call and the stored routing information to the second mobile switching center, wherein the stored routing information associates the directory number with the second mobile switching center; f) if the stored routing information is expired or if the return result from the local number portability data storage device does not include the stored routing information, querying the external number portability database for current routing information associated with the directory number; g) receiving a return result from the external number portability database; h) determining if the return result from the external number portability database includes the current routing information; i) if the return result from the external number portability database includes the current routing information, forwarding the incoming call and the current routing information to a third mobile switching center, wherein the current routing information associates the directory number with the third mobile switching center; and j) storing the current routing information and time information associated with a date and time when the associated number portability query was performed in the local number portability data storage device in relation to the directory number.