Different Types of Phone Wiring-Residential and Commercial
Phone wiring has undergone a series of evolutions in the past few decades. “Back in the day”, when phones were more of a novelty than a piece of technology that everybody required, it consisted of two wires run to a single location in the home or business that required power to be applied to the line (by way of a hand crank) in order for calls to be made. It also required an operator to plug your line into the line of who you were calling. With telco switching technology, that’s no longer the case.
Phone Wiring-The Basics
The bare bones basic phone line only needs two wires, a positive and ground, or, more correctly, tip and ring. Tip and ring is a throwback to the days mentioned above when an operator plugged your line into the recipient’s line. Tip refers to the tip (ground) of the plug and ring (battery/source) refers to the ring behind the tip.
Second Generation Phone Wiring
Pretty soon, the telephone caught on and people started needing more than one phone line. So, houses and businesses were wired for phones with two pairs of wires, green (tip) and red (ring) and black and yellow. The green/red pair were for one line and the black/yellow pair was for the second line. You can still see this configuration when you buy a phone jack from Lowe’s or Home Depot.
Typically, you’d see this type of wiring as a large loop in the house or office building. The loop would start and end at the point of the building where the phone company wires came into the building. This looping allowed for the eventuality that wires would be cut or broken. Since both ends of the loop were connected to the phone company outside wiring, the building wouldn’t lose phone service when the wires were broken or cut. To hook up a phone outlet, the technician would carefully scrape the insulation from a pair of wires and wrap the wire around the terminal posts in the jack.
Generation Three Home Phone Wiring
Pretty soon phone wiring manufacturers came out with something that some phone technicians call three- or four-pair loose wrap phone wire. It resembles what we see today in use, in that it has four pairs, and uses the same color convention in use today (white-blue/blue, white-orange/orange, white-green/green, white-brown/brown). The white wire with the striped color is the tip while the solid-colored wire is the ring. This configuration allowed for four phone lines and still had the wire bundle looping around the house or office building. You’ll find many houses built up until the 1980s with this type of wiring. Hooking up a phone jack continued to consist of carefully stripping the insulation and wrapping the bare wire around terminal posts.
Some of the older wiring resembled this, but with a small difference. Instead of the ring color being solid, it would be broken up with small white stripes. This sometimes, especially in dark attics and basements, led to wiring confusion, so wiring manufacturers and Ma Bell agreed to the change to solid insulation colors for the ring.
Fourth Generation Phone Wiring-Enter the Digital Age
The previous generations of phone wiring methods were pretty easy for anyone with a utility knife and a screwdriver to hook up a new phone jack. However, once we hit the Digital Age that changed. We needed wires that would cut down on the “party line effect” where you can hear other conversations on the line. This is called ‘crosstalk’, because the conversations of other people talking are crossing between phone lines and it’s caused by wiring and line density. It can be defeated by twisting the wire pairs more tightly. Hence, Category 4 and 5 wiring began to be used, along with a different method of attaching the wires.
The wiring convention stayed the same (colors and nomenclature). However, phone jacks lost the ring terminal connections and started making use of punch-down connections, known in the trade as 110 jacks. In order to optimize the line quality, a technician needs to be properly trained and have some experience handling the wiring. Lose the wrong amount of twists during the punch-down/termination phase, and you’ll get crosstalk. A good tech can properly punch down five to ten jacks in less than ten minutes.