A long while back, I started building out a Cold War/MAD/Dr Strangelove audio game that would have used a multi-line red telephone (basically, a high stress choose your own adventure). Never got past the initial game dev side to start working on the soft/hardware implementation side, but might have to dink around with Asterick…
My friend told me that it wasn't difficult at all, I think he got the basic setup for it in few hours, and I think once he got it set up, it wasn't difficult to simply add more phone numbers and map them to MP3's or WAV files.