Do a google search on beige box. It is pretty much a phreaker's (phone hacker) tool. Most of the time it is cheaper to buy a used one from a pawnshop or eBay by the time you build one. Just make sure you use clips with bed of nails so you don't have to strip wires.
This is CABL.com posting #162129. Tiny Link: cabl.co/mQk9