Abstract: A Smart Card Based System for telephone-securized transactions. The system includes a telephone terminal (10) connected to a server (30) and a package or unit (40) incorporating a keypad (42), a smart card (48) and sound signal transmission device. The transmission of the information of the card to the server takes place by way of sound signals and the telephone terminal. In the other direction, the information is addressed in vocal manner to the user, who types them on the keypad (42) of the unit (40). Application to securized teletransactions, particularly electronic funds transfer.