A messaging unit (16) equipped with a cellular transceiver (38) is attached to a truck trailer (12) located within a communications network (10). The messaging unit (16) generates a data message in response to the occurrence of a reporting event. Upon generation of a data message, the cellular transceiver...http://www.google.de/patents/US5539810?utm_source=gb-gplus-sharePatent US5539810 - Data messaging in a communications network
