Abstract: The invention provides a system for securing the access of a remote computer terminal (130) to a centrally located host computer (300). The system includes a first security circuit (200) interconnected with a calling telephone (100), a calling modem (110), and the remote computer terminal (130) at the remote location for automatically dialing the number of the called telephone (310) at the location of the central host computer (300). A second security circuit (350) is located at the central host computer (300) and is interconnected with the called telephone (130), the called modem (330), and the central host computer (300). Upon receipt of the user identification code, the second security circuit (350) compares the user identification code with a stored code and, if verified, sends an acknowledgment signal back to the first security circuit (200).