This adjunct processor arrangement performs a centralized call screening function to provide computer port access security. Every call origination in the telephone switching system from a calling party to a protected computer port is interdicted by the telephone switching system and routed to the adjunct processor. The calling party receives a series of prompts from the adjunct processor to provide identification information, such as login, password, and voiceprint information. The adjunct processor validates the identity of the calling party using this identification indicia and initiates a callback operation. The adjunct processor disconnects the calling party from the connection, calls the calling party back and then uses the data call transfer capability of the telephone switching system to connect the calling party to the computer.