An identity verification device comprises a cellular telecommunications modem and a fingerprint scanner coupled to the modem, the verification device being configured for storing first fingerprint data in an enrollment process and being operable, in response to the modem receiving a verification command via a cellular telecommunications network, to perform a verification process in which the fingerprint scanner scans a fingerprint to obtain second fingerprint data, the first and second fingerprint data are compared with each other, and in the event of a match between the first and second fingerprint data, the modem transmits a response signal to a predetermined destination via the telecommunications network. The device may be used in a networked telecommunications system in which the electronic transactions may be initiated by smart cards and other devices.