A system having at least one RFID chip (30) belonging to a packaging unit (1) and being surrounded by a metal outer casing (11) of the packaging unit (1), said chip comprising a switching circuit (32) and an antenna structure (31), and a transmitting/receiving unit (41) for transmitting a transmission signal (42) and/or receiving a response signal (43) from the RFID chip (30), an evaluating unit (44) connected to the transmitting/receiving unit (41) which can evaluate the response signal (43), wherein the RFID chip (30) has an operating frequency which is in a frequency band (50) below a range of a blocking frequency (54) which is determined by the conductivity of the metal outer casing (11) and its thickness and wherein the RFID chip (30) has a sensor which influences the response signal (43) of the RFID chip (30), the sensor responding to condition inside the metallic outer casing and the out sent response signal corresponding to the condition.