Abstract: An apparatus communicating with data systems, and a method of communicating with data systems. In an apparatus (10, 49) communicating with a high secrecy and high security on-line verification data system (40) and an off-line verification data system (18) of a lower secrecy and security level, a person in possession of a card (21, 22, 12, 24) inputs the card into the apparatus (10, 49). The data are read from the card and input to a security module (50) of the apparatus. On the basis of the data read from the card, the apparatus (10, 49) identifies the card as a card belonging to the on-line data system or the off-line data system. Within the security module (50) of the apparatus (10, 49), a keyboard (46) is arranged, which is adapted to be activated by the person in possession of the card for inputting a personal authentication code (actually a PIN-code) into the security module.