I've been told by the organizer of http://bsideshuntsville.org/ to present my rotary phone at this coming bsides. My idea for displaying the phone will be writing jukebox software on my Mac which listens for the number being dialed on the rotary phone. Depending on the number dialed, the computer will play a song. When dialing 0, it'll turn on the speaker so that they can hear the music playing over the speaker.
I'll just take my current firmware and modify it to not have any of the phone features and to only display the number being dialed if it's not 0. I'll place the source code in a separate repository on github for people to read and have the source code and other things displayed on my MacBook's screen for people to see.