The story
Generally, for any truck travelling on the German motorways, the distance-based fees can be paid by different means: through the advance purchase of a specific route via the internet or at payment terminals (typically located in fuel stations), or fully automated through the use of OBUs that are professionally installed in the trucks. Through the use of satellite navigation, the position and the trip are data stored in the OBU which enable the device to determine the tolling fees that apply for the route driven. The data collected in the OBU are transferred to the data center by mobile data communication (GSM), and processed for billing. The fact that the system is "satellite based" relates to the positioning only, not to the communication of the OBU to the data center.
To prevent avoidance of toll payments (e.g. by switching off the OBUs), the trucks are photographed at approximately 300 toll enforcement gantries, and checked by approximately 450 mobile checking stations. The data generated from these compliance checks are compared in the central computing system, and enforcement measured being started. The non-compliance rate is published as being consistently less than 1%.
Plans to export the specific German solution to other countries were not realized, but a number of GNSS-based tolling solutions were implemented in European countries for distance-based charging of trucks. Plans to expand the system to value-added services, such as fleet management, were not implemented.
From Wikipedia’s article on Toll Collect, shared under CC BY-SA 4.0.5