Abstract: A telephone security apparatus placed at a subscriber station intercepts and screens incoming calls direct to a terminal through a modem. The security apparatus prevents completion of a connection to the terminal equipment unless the incoming call provides a predefined access code and the call is found to have been made from the remote subscriber station to which the predefined access code has been assigned. The security apparatus automatically dials back the subscriber station corresponding to the access code given on the incoming call. A microprocessor-based embodiment is described.