15.3. Four-Pair Wiring Schemes

For a horizontal cable segment, the TIA/EIA 568 standard recommends the use of four-pair cables with all eight wires terminated in 8-position jack connectors at each end of the link. The entire twisted-pair cabling system should be wired "straight through." This means that pin 1 of the connector at one end of a horizontal cable is wired to pin 1 of the connector at the other end, and so on for all eight connections. This keeps the structured cabling system very simple and straightforward.

15.3.1. Tip and Ring

The words tip and ring are used to identify wires in a wire pair. Most single telephone circuits require just two wires to deliver what is known in the telephone industry as plain old telephone service (POTS). These two wires are identified as "tip" and "ring" by the industry. These names date from the earliest days of manual telephone switchboards, when operators made connections between telephone lines using patch cables with plugs on the end. The plugs had a tip and a ring conductor on them; hence the names for the two wires still used to make a basic telephone connection. Each pair of wires in a modern communications cable is still considered to have a designated tip conductor and ring conductor, labeled T1 and R1 for the first pair, T2 and R2 for the second pair, and so on.