Abstract: An ATM is provided with a loudspeaker and a microphone. The loudspeaker generates white noise which is picked up by the microphone. The detected signal constitutes an acoustic signature which changes if the ATM is tampered with, for example by inserting some fraudulent mechanism into the ATM to intercept banknotes before they reach the output slot of the ATM. If any such change is detected then an alarm can be raised.

Abstract: A currency cassette (10) has a printed circuit board (80) secured to one of its side walls, the board (80) having mounted thereon a microprocessor, a RAM, a real time clock chip, and battery means for supplying power for the board (80). First (208) and second switches are respectively operatively associated with the lid (14) of the cassette (10) and with a shutter which, when opened, permits currency notes to be extracted in operation from the cassette (10). Opening of the lid (14) or the shutter causes the appropriate switch to be actuated. Each switch is connected to the printed circuit board (80), and the microprocessor is arranged, in response to actuation of either of the switches, to store in the RAM data indicating which switch was actuated and the date and time of day when the relevant switch was actuated. The switches and printed circuit board (80) provide an effective tamper indicating system for the cassette (10).