Plug it in and call it with a cell phone. Good luck!
I've always had an interest in cardboard. When I was 7 I made a car out of it, but I thought that cardboard models were too simple. I decided to make something out of cardboard that was more complicated. I decided on a phone. And yes, it does work. It took the better part of a day to make, but wasn't very difficult to do so. I'm only 14 and have very few skills in wiring and technology, but was still able to to this easily.
You don't need very many things to make this project. You need: 1. Scotch tape 2. Pen (or sharp object) 3. Scissors 4. X-acto knife or other kind of blade 5. Fine point Sharpie 6. Magazine to protect your table when cutting cardboard 7. Old telephone you can completely destroy 8. CARDBOARD!
Step 2: Take the phone apart
The phone i chose was near impossible to open. the base was fairly easy thanks to a screwdriver, but the top part was held together so tightly, i had to pry pieces off of it before i could twist it apart. From there, i unscrewed the circuit board from the phone. I then had all the necessary pieces to work a phone.