Phone companies most often use this type of wire, but increasingly it has found its way into computer networks. Copper wires attract other signals just like a radio antenna. Putting copper wires together means they can interfere with each other. To prevent this interference two copper wires are twisted together, in effect canceling out emitted signals from the other wire and protecting the set from outside noise. Normally, twisted-pair cables are color coded and coated with plastic jackets.
Cables can have more than one set of twisted-pair.
Because of this telephone and data cable runs can be made at the same time. Each standard or rating refers to twists per foot, conductor size, and electrical characteristics. Although there are lower ratings, this is the first that supports high-speed data. Category 3 offers data rates in ethernet networks at 10Mbps, but can support up to 16Mbps in token ring environments. In addition, this is the cable used for most phone line installations.