[ The reason I'll be busy is I'm doing two hackathons for my work, a geospatial hack - http://2013.foss4g.org/geohack/ and a fashion hack - https://climate.makes.org/thimble/climate-change-and-fashion-hackathon ]
Hardware list -
Bakelite telephone. The earpiece is the original one but the microphone was a carbon type so I replaced this with an electret capsule.
USB audio adaptor. These can be imported from China via ebay.
Toggle switch and microswitches. I've put a "sound/silent" toggle on the front, plus and LED with chrome bezel - all from the junk box. The "sound/silent" plate for the toggle switch is from an old cine projector.
MCP23008 port expander. To interface the switches and LED to the Raspberry Pi using I2C (SMBUS).
WiPi - wifi adapter.
Other than a few bits of wire, stripboard and the odd connector and nuts and bolts that's about it.
More pictures -