On-line units bring their users a benefit of real time monitoring of vehicles and such a degree of position updating as required. Additionally, all data transfers (logbook data, unit settings, or diagnostic and service functions of the supplier) are executed via GSM network, which means that no actions in the vehicle are necessary once the unit has been installed. Princip a.s. Company is a renowned manufacturer of GSM/GPS telematic units and is closely co-operating with all GSM operators on the Czech market.