[michelb]

I made something similar using another instructable(1) with a simpler approach a couple of years ago. Great fun, and relatively easy to do (it was my first 'hardware' project and I knew nothing about electronics).

I kept the speakers and all intact and it still sounds fine. I loaded it up with some fairytale stories, 1 for each single number you can dial.

1: https://www.instructables.com/Fairytale-Phone/