If you already had a four wire line running to the box, then you don't need additional wires. Just use the yellow and black of the first wire as the red and green of the second line. Then it is trial and error although most have color coded screw heads. Wrap extra wires back around the insulated part of the phone line. For Melissa, most phone companies charge beaucoup extra bucks to do the inside part of the installation tacked on to the charge for the office, pole, and wiring to their side of the box.