Abstract: A differential positioning system (10) includes components of a satellite-based or land-based positioning system (12) and components of a mobile communications network (14). The differential positioning system (10) provides accurate and immediate position information to a mobile unit (17). A transmitter site (40) of a mobile communications network (14) is associated with a reference positioning receiver (38). The reference positioning receiver (38) generates correction data for transmission to the mobile unit (17). The mobile unit (17) includes a mobile communications device (42) for receiving the correction data generated by the reference positioning receiver (38) and a mobile positioning receiver (24) for generating a position fix. The mobile unit (17) refines the position fix generated by the mobile positioning receiver (24) using correction data received by the mobile communications device (42).

Abstract: A communication system includes mobile units, a network switching center, and service centers to provide a variety of enhanced services to the mobile units. The service centers and/or the network switching centers determine directions from an origination location to a destination location. The directions, which may comprise multiple segments separated by separator signals, are communicated to the mobile unit using a communication network. The mobile unit may present each segment of the directions to a user. In one embodiment, the mobile unit generates a service message specifying an origination location and a destination location. The directions are determined in response to the service message.