Thanks. How much soldering and stuff will it take to put it together? The tin is about 3 3/4" x 2 1/3" I think one of the harder parts will be making the cover for that.
Check out the very first post in this thread. It's got a link to an electronics module that would fit in there and is ready to go out of the box (not sure if batteries are included, though). It's got 4 buttons and a speaker pre-wired. Just plug it into your pc and use the free software from the product page to program your sounds onto it. You can just use a single button and have it play a different sound with each press (Ringing, Answer sound, hang up sound).
And if you need audio files, the actual files used by the production can be found here:
http://db.tt/fbmHydNi
Hope this helps,
-Shawn