Re: Back door in to the comms systems
"Was there an option to play thermonuclear war?"
That was just a batch file located on the local machine. Forced the modem to make all the correct connection noises, but didn't actually require a telephone line. Echoed the "responses" from the "far end" to the console. The version that used ANSI.SYS[0] to draw the screen was almost convincing.
[0] Or NANSI.SYS if you had clues.