A method for continuous determination of a person's presence in a public transport conveyance is proposed, where a customer medium comprising an RF transceiver is assigned to the person, where at least one reading device per passenger compartment or car is provided for data communication with the customer media in the conveyance, which is connected to a computer serving as an on-board unit for the purpose of data communications, where these are also connected to each other in the case that several reading devices are provided, where an on-board unit serving as the main on-board unit is assigned to a passenger compartment or car if several passenger compartments or cars are present, and the other passenger compartments or cars are assigned to on-board units serving as secondary on-board units, which are connected to the main on-board unit for the purpose of data communication, where the customer medium is in a “sleep” mode upon entering the transport in order to keep energy consumption as low as possible.