Telephone Wiring Diagram - Ask-The-Electrician Summary: This telephone wiring diagram with photos and instructions will show you the direct steps to correctly wiring a telephone jack. Wiring a Telephone Jack After installing the Cat 3 - 3 pair phone wire I am ready to install the wall jack. Understanding the Connection Types for Your TV, Internet Identify multiple ways to connect to your television, home theatre or audio system. Understanding Telephone Wire and Wiring Colors For Correct Repairmen in fact refer to the wires in terms of "pairs", so technically a standard four wire telephone line has two pairs. LINE 1 uses the red-green pair. Line 2 uses the yellow-black pair. The cable is very small, as are the wires inside, and should not be confused with electrical wires, which are much larger.