A method for verifying and identifying users, and for verifying users' identity, by means of an authentication device capable of transmitting, receiving and recording audio or ultrasonic signals, and capable of converting the signals into digital data, and performing digital signal processing. Voice pattern(s) and user(s) information of one or more authorized user(s) are recorded and stored on the authentication device. User(s) identification is verified by inputting to the authentication device a vocal identification signal from a user, and comparing the voice pattern of the vocal identification signal with the recorded voice pattern(s) of the authorized user(s), and if a match is detected issuing an indication that the user is identified as an authorized user.