Overview

Telephony wiring dates back 125 years ago, to the days when Alexander Graham Bell was tinkering with the first telephone. Telephones traditionally have used loop current for voice communications and signaling transmission. For many years single-pair (two-wire) cabling had supported telephones working behind a PBX system, but system equipment innovations, beginning with the introduction of digital switching and stored program call control, forced changes in the cabling infrastructure during the late 1970s. The first generation of proprietary PBX telephones, first electronic and then digital, required multiple wiring pairs to support the more advanced features and functions available with the new technology. At the same time, the early data LANs required a wiring infrastructure of their own, based on coaxial cable. As customer premises voice networks and data networks evolved in the mid-1980s, issues such as a common infrastructure and increasing transmission bandwidth requirements needed to be addressed. The existing telephony wiring system, fine for voice but inadequate for data, needed a major overhaul.

In 1985, two standards committees began working on specifications for a generic telecommunications cabling system to support a mix of communications media (voice, data, video) in a multivendor environment. The TIA and the Electronic Industries Association (EIA) formed a joint committee known as the EIA/TIA 41.8 Committee. After 6 years of work, the TIA/EIA 568 standard was issued. TIA/EIA 568 is more formally known as the Commercial Building Cabling Standard and outlines specifications for a generic telecommunications cabling system. The American National Standards Institute (ANSI) also...