Universal Service Ordering Code

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What Does Universal Service Ordering Code Mean?

The Universal Service Ordering Code (USOC) is a specification system developed by Bell Systems in order to connect equipment used in customer premises, such as homes and offices, into the greater public network. The USOC is basically a naming convention for registered jack (RJ) wiring configurations used in telephone jacks or connectors that are still in active use today. The most basic example is the RJ-11 jack, which comes in many variants, used to connect telephones into the network interface.


Techopedia Explains Universal Service Ordering Code

The Universal Service Ordering Code serves to identify telecommunication services equipment. This was developed by Bell Systems and introduced in the 1970s by AT&T in order to connect telecommunications equipment in customer premises into the public network lines so that they can receive telephone services. These codes were later adapted to some extent by the FCC as Part 68, Subpart F, Section 68.502.

The specification includes the physical construction, wiring and signal semantics used in the jacks that are primarily named using the letters RJ followed by two digits that represent the type of jack and then letter suffixes that are added to further indicate some minor variations. The most commonly used today are RJ11 and RJ45, which are used in telephones and modems and in network connections, respectively.

Variations specified by the letter suffix:

  • C — Identifies a surface or flush-mount jack
  • W — Identifies a wall-mounted jack
  • S — Identifies a single-line jack
  • M — Identifies a multi-line jack
  • X — Identifies a complex multi-line or series-type jack

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.