A non-real time messaging system (200) for targeting messages to a subscriber unit (222) comprises a synchronized profile of where a subscriber unit should be located (a predetermined base transmission area for transmission of messages to the subscriber unit) maintained between a controller (212) and the subscriber unit. The subscriber unit detects when the subscriber unit is not within the receiving range of a predetermined base transmission area, informs the controller and the controller directs subsequent transmissions to an area identified by the subscriber unit and otherwise transmits subsequent messages to the predetermined base transmission area. The system further includes a plurality of base receivers (217) coupled to the controller for receiving transmissions from the subscriber units and allowing the controller to detect when the subscriber unit is not within the receiving range of a predetermined base transmission area.