[ipdashc]

Completely overkill for just an intercom, but an analog telephone adapter would let you connect those to a VoIP server (like Asterisk, etc). Could be cool.

For just a hotline/intercom setup, I think a telephone line simulator might do the job, but those seem stupidly expensive!

EDIT: The other reply seems a lot more knowledgeable, ignore this one

[drewzero1]

Thanks! I was looking into a line simulator, but yeah they're expensive!

I thought about setting something up with an old PBX from work, but they're too new for pulse dialing. I was trying to figure out if I could build something with old modems but never got anywhere with that.