Abstract: A call delivery system (10) for delivering a call to a mobile unit (12) on a vehicle (14) includes both a data communications network (16) and a mobile voice communications network (20). The mobile unit (12) generates call delivery information and communicates this information to a platform (18) using the data communications network (16). The platform (18) receives a call for the mobile unit (12). The platform (18) retrieves call delivery information received from the mobile unit (12) and establishes communications between the platform (18) and the mobile unit (12) using the mobile voice communications network (20). The platform then completes the call between the caller (36, 40, 44) and the mobile unit (12). Alternatively, the platform (18) can generate a call back message for transmission to the mobile unit (12) using the data communications network (16).