Tracker Automatic Vehicle Locators (AVL) includes a family of telemetry devices that provides monitoring of mobile assets with or without messaging and asset management and control. There are two major lines within the Tracker AVL family from Teletouch Communications. While both products use global positioning satellites, one product line is designed to operate over terrestrial networks and the other uses satellites to transmit information. These devices help customers monitor and track their vehicles, detached trailers and any other mobile assets. Together with the company's GeoFleet mapping software, each system can be tailored to provide mapping, Web-based management and messaging.