The invention provides a system for monitoring a container for transporting cargo. The system includes an onboard device attached to the container and a central computer system. The central computer system processes alerts transmitted by the onboard device. The onboard device includes a processor/sensor component and an antenna component. The processor/sensor component comprises a processor for controlling the device. The processor/sensor component also includes one or more sensor in communication with the processor for sensing container conditions. A satellite modem in the processor/sensor component transmits alerts relating to container conditions and other satellite communications. The antenna component includes a satellite antenna, which is connected to the satellite modem.