Residential Telephone Wiring Basics - whoopis Sometimes, in older boxes, the customer test jack has a short phone wire tail and connector already plugged in. In this case, keep in mind that when you unplug that little tail and plug in your own phone to test, your house's wiring is now physically disconnected from the box.[PDF] Lets go over the basics of telephone wiring. telephone wiring is really simple and logical. Take a walk around your house, and we'll figure it out together. The telephone company, bless their souls, provides you with service through four wires or more wires leading to the outside of your house (there is actually more to it than that, but you don't need to know more to work on your own stuff).