Re: Rotary dials
You can even buy the parts and breadboard a rotatary to DTMF. A pi or old laptop with serial port (sense a handshake line) can do it. Even easier if old laptop has a built in modem (AT D command).
Some exchanges and ATAs do still support pulse dialing.
Two analogue phones (any kind) and a 6V battery all in series makes an intercom. We used top & bottom wire of a fence when we were kids.