We all have old phones. Why not turn them into an intercom for your kids tree house. Or turn two old cordless phones into home base walkie talkie. Here is how.
Step 1: Materials
In-Line coupler (I got mine at Frys for 1.49)
9 volt connector (radio shack, or cut it out of some old piece of junk)
milk (helps keep you hydrated and keeps bones strong)
300 ohm resistor or close to it
black electrical tape
two telephone cords. (CAT 1 cable)