Registered jack

Registered jack

A registered jack (RJ) is a standardized physical interface — both jack construction and wiring pattern — for connecting telecommunications equipment (commonly, a telephone jack) or computer networking equipment to a service provided by a local exchange carrier or, sometimes, a long distance carrier. The standard designs for these connectors and their wiring are named
RJ11, RJ14, RJ45, etc. These interface standards are most commonly used in North America, though some interfaces are used world-wideFact|date=April 2008.

The physical connectors that registered jacks use are of the modular connector type, except RJ21X which is a 25-pair Amphenol connector. For example, RJ11 uses a 6 pin 4 conductor (6P4C) modular plug and jack.

Naming confusion

There is much confusion over these connection standards. The six-position plug and jack commonly used for telephone line connections may be used for RJ11, RJ14 or even RJ25, all of which are actually names of interface standards that use this physical connector. The RJ11 standard dictates a 2-wire connection, while RJ14 uses a 4-wire configuration, and RJ25 uses all six wires. The RJ abbreviations, though, only pertain to the wired jack (hence the name "Registered Jack"); it is commonplace but not strictly correct to refer to an unwired plug connector by any of these names.

Plugs and jacks of this type are often called modular connectors, which originally distinguished them from older telephone connectors, which were very bulky or wired directly to the wall and therefore not accommodating of modular systems. A common nomenclature for modular connectors is e.g. "6P" to indicate a six-position modular plug or jack. Sometimes the nomenclature is expanded to indicate the number of positions that contain conductors. For example, a six-position modular plug with conductors in the middle two positions and the other four positions unused is called a 6P2C. RJ11 uses a 6P plug; furthermore, it often uses a 6P2C. (The connectors could be supplied more pins, but if more pins are actually wired, the interface is no longer an RJ11.)

Alternative terminologies are sometimes used, including 6×2 and 6/2.

Registered jacks were originally the subject of Bell System Universal Service Ordering Codes.A USOC is a code one can use on an order for telephone service to specify the kind of service ordered. For example, to order a new telephone extension installed the subscriber might specify the USOC "RJ11W" in order to get a 6P2C jack for a conventional wall mounted single line telephone installed. People sometimes use "USOC" to refer to the service specification itself, though the USOC is just the name of it. With respect to registered jacks, the complete specification was registered (at one time with the US government) — hence the name. Though it's awkward to refer to a standard for a jack as a jack, it is nonetheless the conventional terminology. The registered jack is the type of physical interface and the USOC is a name for that type of physical interface.

It is important to note that a USOC does "not" always indicate precisely which connector to use.

Twisted pair

While the plugs are generally used with a flat cable (a notable exception being Ethernet twisted-pair cabling used with the 8P8C modular plug), the long cables feeding them in the building wiring and the phone network before them are normally twisted pair. Wiring conventions were designed to take full advantage of the physical compatibility ensuring that using a smaller plug in a larger socket would pick up complete pairs not a (relatively useless) two half pairs but here again there has been a problem. The original concept was that the centre two pins would be one pair, the next two out the second pair, and so on until the outer pins of an eight-pin connector would be the fourth twisted pair. Additionally, signal shielding was optimised by alternating the “live” (hot) and “earthy” (ground) pins of each pair. This standard for the eight-pin connector is the USOC-defined pinout, but the outermost pair are then too far apart to meet the electrical requirements of high-speed LAN protocols. Two variations known as T568A and T568B overcome this by using adjacent pairs of the outer four pins for the third and fourth pairs. The inner four pins are wired identically to RJ14. (See: Category 5 cable.)

History and authority

Registered Jacks were introduced by the Bell System in the 1970s under a 1976 FCC order ending the use of protective couplers. They replaced earlier, bulkier connectors. The Bell System issued specifications for the modular connectors and their wiring as Universal Service Ordering Codes (USOC), which were the only standard at the time.

When the US telephone industry was opened to more competition in the 1980s, the specifications were made a matter of US law, ordered by the Federal Communications Commission (FCC) and codified in the Code of Federal Regulations, 47 CFR 68, subpart F.

In January 2001, the FCC turned over responsibility for standardizing connections to the telephone network to a new private industry organization, the Administrative Council for Terminal Attachment (ACTA). The FCC removed Subpart F from the CFR and added Subpart G, which delegates the task to the ACTA. The ACTA published a standard called TIA/EIA-IS-968 which contained the information that was formerly in the CFR. The current version of that standard, called TIA-968-A, specifies the modular connectors at length, but not the wiring. Instead, TIA-968-A incorporates a standard called T1.TR5-1999 by reference to specify the wiring. Note that a Registered Jack name such as RJ11 identifies both the physical connectors and the wiring (pinout) of it (see above).

International use

The modular jack was chosen as a candidate for ISDN systems. In order to be considered, the connector system had to be defined under international standards. In turn this led to ISO 8877. Under the rules of the IEEE 802 standards project, international standards are to be preferred over national standards so the modular connector was chosen for IEEE 802.3i-1990, the original 10BASE-T twisted-pair wiring version of Ethernet.

Registered jack types

The most familiar registered jack is probably the RJ11. This is a 6 position modular connector wired for one phone line, and is found in most homes and offices in North America for single line telephones.

RJ14 and RJ25 are also fairly common, using the same size connector as RJ11, but with two and three phone lines, respectively, connected.

Essentially all one, two, and three line telephones made today (2006) are meant to plug into RJ11, RJ14, or RJ25 jacks, respectively.

The true RJ45(S) is an extremely uncommon registered jack, but the name "RJ45" is also used quite commonly to refer to any 8P8C modular connector.

Many of the basic names have suffixes that indicate subtypes:

*C: flush-mount or surface mount
*W: wall-mount
*S: single-line
*M: multi-line
*X: complex jack

For example, RJ11 comes in two forms: RJ11W is a jack from which you can hang a wall telephone, while RJ11C is a jack designed to have a cord plugged into it. (You can plug a cord into an RJ11W as well, but it usually isn't as aesthetic as a cord plugged into an RJ11C).

Common types

*RJ11C/RJ11W: 6P2C, for one telephone line (6P4C with power on second pair)
*RJ14C/RJ14W: 6P4C, for two telephone lines (6P6C with power on third pair)
*RJ25C/RJ25W: 6P6C, for three telephone lines

Uncommon types

*RJ2MB: 50-pin miniature ribbon connector, 2-12 telephone lines with make-busy
*RJ12C/RJ12W: 6P6C, for one telephone line ahead of the key system
*RJ13C/RJ13W: 6P4C, for one telephone line behind the key system
*RJ15C: 3-pin weatherproof, for one telephone line
*RJ18C/RJ18W : 6P6C, for one telephone line with make-busy arrangement
*RJ21X: 50-pin miniature ribbon connector, for up to 25 lines
*RJ26X: 50-pin miniature ribbon connector, for multiple data lines, universal
*RJ27X: 50-pin miniature ribbon connector, for multiple data lines, programmed
*RJ31X: 8P8C (although usually only 4C are used), Often incorrectly stated as allowing alarm (fire and intrusion) equipment to seize a phone line, the jack is actually used to disconnect the equipment from the phone line while allowing the phone circuit to continue to the site phones.
*RJ38X: 8P8C, similar to RJ31X, with continuity circuit
*RJ41S: 8P8C keyed, for one data line, universal
*RJ45S: 8P2C + keyed, for one data line with programming resistor
*RJ48S: 8P8C, for four-wire data line (DDS)
*RJ48C: 8P8C, for four-wire data line (DSX-1)
*RJ48X: 8P8C with shorting bar, for four-wire data line (DS1)
*RJ49C: 8P8C, for ISDN BRI via NT1
*RJ61X: 8P8C, for four telephone lines
*RJ71C: 12 line series connection using 50 pin connector (with bridging adapter) ahead of customer equipment. Mostly used for call sequencer equipment.

"Unofficial" (incorrect) plug names

These "RJ" names do not really refer to truly existing ACTA RJ types:
*"RJ9", "RJ10", "RJ22": 4P4C or 4P2C, for telephone handsets. Since telephone handsets do not connect directly to the public network, they have no Registered Jack code whatsoever.
*"RJ45": 8P8C, informal designation for T568A/T568B, including Ethernet; not the same as the true RJ45/RJ45S
*"RJ50": 10P10C, for data

Other compatible Types

* GG-45 for 10GBit Ethernet

External links

* [ RJ glossary]
* [ TIA-968-A] - Contains dimensions for jacks and plugs.
* [ RJ reference] - Descriptions and applications
* [ Administrative Council for Terminal Attachments]

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Registered Jack — Saltar a navegación, búsqueda Distintos conectores RJ Un registered jack (RJ) es un standar para interfaz física, tanto para la construcción de conectores como para el diseño del cableado, para la conexión de equipos de telecomunicaciones o de… …   Wikipedia Español

  • Registered Jack 9 — RJ9 diagramme du connecteur RJ9 Le connecteur RJ9 ou Registered Jack 9 est le plus petit des plugs modulaires. Il s agit d un connecteur de téléphone généralement utilisé pour relier la base au combiné via un câble torsadé. Le RJ9 dispose de 4… …   Wikipédia en Français

  • Registered Jack — Для улучшения этой статьи желательно?: Найти и оформить в виде сносок ссылки на авторитетные источники, подтверждающие написанное. Викифицировать статью …   Википедия

  • Registered jack — Este artículo está huérfano, pues pocos o ningún artículo enlazan aquí. Por favor, introduce enlaces hacia esta página desde otros artículos relacionados …   Wikipedia Español

  • Registered Jack — RJ Steckverbindungen, die ersten beiden Buchstaben stehen für Registration Jack (genormte Buchse), sind von der US amerikanischen Federal Communications Commission (FCC) genormte Steckverbindungen für Telekommunikationsverkabelungen. Die… …   Deutsch Wikipedia

  • Jack (prise) — Pour les articles homonymes, voir Jack. Fiche Jack stéréo + vidéo, stéréo + microphone ou stéréo + contrôle (4 contacts), utilisée principalement dans les caméras, les enregistreurs ou les baladeurs …   Wikipédia en Français

  • Jack (connector) — In electronics, a jack is generally a socket (female) connector, but because the related term jack plug is often abbreviated to just jack, confusion can easily arise. To avoid confusion, the specific terms plug or socket are often preferable. The …   Wikipedia

  • Jack Davis (industrialist) — Jack Davis Born 1933 (age 77–78)[1] Residence Amherst, New York[2] …   Wikipedia

  • Jack Barry (singer) — Jack Barry was the stage name of Jacob Belser (December 15 1909 September 23 1982), who sang on the radio from 1930 1936 on The Jack Barry Show. Early life Barry was the first child of Osias Belser (1891 1918) and Anna Belser (1890 1962). His… …   Wikipedia

  • Jack Speiden — (b. 1900 d. ????) was an American stockbroker and ranch owner. Speiden fought in both World Wars, attended Yale and received a letter for football while playing on the hockey team, taught in China, worked on Wall Street, bought a ranch, and ran… …   Wikipedia