I have a similar project, 90% finished, with a wifi enabled Rpi4 that uses asterix as a soft phone and can be used as a classic rotary. Some notes:<p><pre><code> - As the creator of this music phone I had hoped to keep the original mic and speaker. This turned out to be more work than I was willing to do as those were both 24V devices, not suitable for Rpi integration without extra electronics.
- I also had hoped to keep the original handle chord. This also turned out to to be impossible as the original mic and speakers shared a common 24V+. So 3 wires in total in the chord, I needed 4 for the new mic and speaker.
- I also ripped out most of the ringer mechanics, but kept the bells. The bells are now hit with a piece of heat shrink tube on the end of a small motor.</code></pre>