Our 25ft 4 conductor RJ11 / RJ14 telephone line cable is designed for use with both Business and Home telephone systems. These heavy duty cables will work with 1 or 2 line phones. Plug and play ready for fax lines, modems, cordless or standard phones. pin1 -- pin4 (black)
pin2 -- pin3 (red)
pin3 -- pin2 (green)
pin4 -- pin1 (yellow)