Registered jack
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/Rjxx.jpg/220px-Rjxx.jpg)
- Eight-position, eight-contact (8P8C) plug, as used for RJ45S, RJ49, RJ61, and others (though shown wired in a pattern incompatible with RJ61)
- Six-position, six-contact (6P6C) plug, which can be used with RJ25, RJ14, and RJ11
- Six-position, four-contact (6P4C) plug, which can be used with RJ14 and RJ11 (and will carry lines 1 and 2, but not line 3, of an RJ25)
- Four-position, four-contact (4P4C) plug, used for connecting a telephone handset and base
- Six-position, six-contact (6P6C) jack, which could be wired as RJ11, RJ14, or RJ25
A registered jack (RJ) is a standardized
The connectors used for registered jack installations are primarily the modular connector and the 50-pin miniature ribbon connector. For example, RJ11 and RJ14 use female six-position modular connectors, and RJ21 uses a 25-pair (50-pin) miniature ribbon connector. RJ11 uses two conductors in a six-position female modular connector, so can be made with any female six-position modular connector, while RJ14 uses four, so can be made with either a 6P4C or a 6P6C connector.
Naming standard
The registered jack designations originated in the standardization process of telephone connections in the Bell System in the United States, and describe application circuits and not just the physical geometry of the connectors. The same modular connector type may be used for different registered jack applications. Modular connectors were developed to replace older telephone installation methods that used hardwired cords or bulkier varieties of
Strictly, Registered Jack refers to both the female physical connector (modular connector) and specific wiring patterns, but the term is often used loosely to refer to modular connectors regardless of wiring, gender, or use, commonly for telephone line connections, but also for Ethernet over twisted pair, resulting in confusion over the various connection standards and applications. For example, the six-position physical connector, plug and jack, is identically dimensioned and inter-connectable, whether it is wired for one, two, or three lines. These are the RJ11, RJ14, and RJ25 interfaces. The RJ standards designations only pertain to the wiring of the (female) jacks, hence the name Registered Jack. It is commonplace, but not strictly correct, to refer to the unwired connectors or the (male) plugs by these names.
The nomenclature for modular connectors is based on the number of contact positions and the number of contacts present. 6P indicates a six-position modular plug or jack. A six-position modular plug with conductors in only the middle two positions is designated 6P2C; 6P4C has four conductors in the middle positions, and 6P6C has all six. An RJ11 without power, if made with a 6P6C connector, has four unused contacts.
History and authority
Registration interfaces were created by the Bell System under a
The wired communications provider (telephone company) is responsible for delivery of services to a minimum (or main) point of entry (
In the
Registered jacks replaced the use of protective couplers provided exclusively by the telephone company. The new modular connectors were much smaller and cheaper to produce than the earlier, bulkier connectors that were used in the Bell System since the 1930s. The Bell System issued specifications for the modular connectors and their wiring as Universal Service Order Codes (USOC), which were the only standards at the time. Large customers of telephone services commonly use the USOC to specify the interconnection type and, when necessary, pin assignments, when placing service orders with a network provider.
When the U.S. telephone industry was reformed to foster competition in the 1980s, the connection specifications became federal law, ordered by the FCC and codified in the Code of Federal Regulations (CFR), Title 47 CFR Part 68, Subpart F,[2] superseded by T1.TR5-1999.[3]
In January 2001, the FCC delegated responsibility for standardizing connections to the telephone network to a new private industry organization, the
TIA-968-A, the current version of that standard,[6] details the physical aspects of modular connectors, but not the wiring. Instead, TIA-968-A incorporates the standard T1.TR5-1999, "Network and Customer Installation Interface Connector Wiring Configuration Catalog",[3] by reference. With the publication of TIA-968-B, the connector descriptions have been moved to TIA-1096-A.[4] A registered jack name, such as RJ11, still identifies both the physical connectors and the wiring (pinout) for each application.
Types
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Conector_RJ11.jpg/220px-Conector_RJ11.jpg)
The most widely implemented registered jack in telecommunications is the RJ11. This is a modular connector wired for one telephone line, using the center two contacts of six available positions. This configuration is also used for single-line telephones in many countries other than the United States. It may also use a 6P4C connector, to use an additional wire pair for powering lamps on the telephone set. RJ14 is similar to RJ11, but is wired for two lines and RJ25 has three lines. RJ61 is a similar registered jack for four lines, but uses an 8P8C connector.
The RJ45S jack is rarely used in telephone applications, and the keyed 8P8C modular plug used for RJ45S mechanically cannot be inserted into an Ethernet port, but a similar plug, the non-keyed 8P8C modular plug – never used for RJ45S – is used in Ethernet networks, and the connector is often, however improperly, referred to as RJ45 in this context.
Code | Connector | Usage |
---|---|---|
RJA1X | 225A adapter | Connector for a modular plug to a four-prong jack |
RJA2X | 267A adapter | Connector for splitting one modular jack to two modular jacks |
RJA3X | 224A adapter | Connector for adapting a modular plug to a 12-prong jack |
RJ2MB | 50-pin | 2–12 telephone lines with make-busy arrangement |
RJ11(C/W) | 6P2C
|
Establishes a bridged connection for one telephone line (6P4C if power on second pair) |
RJ12(C/W) | 6P6C
|
Establishes a bridged connection for one telephone line with key telephone system control ahead of line circuit
|
RJ13(C/W) | 6P4C
|
Similar to RJ12, but behind the line circuit |
RJ14(C/W) | 6P4C
|
For two telephone lines (6P6C if power on third pair) |
RJ15C | 3-pin weatherproof | For one telephone line for boats in marinas |
RJ18(C/W) | 6P6C
|
For one telephone line with make-busy arrangement |
RJ21X | 50-pin | Multiple (up to 25) line bridged T/R configuration |
RJ25(C/W) | 6P6C
|
For three telephone lines |
RJ26X | 50-pin | For multiple data lines, universal |
RJ27X | 50-pin | For multiple data lines, programmed |
RJ31X | 8P8C
|
Allows an alarm system to seize the telephone line to make an outgoing call during an alarm. The jack is placed closer to the network interface than all other equipment, and only 4 conductors are used. |
RJ32X | 8P8C
|
Like RJ31X, this wiring provides a series tip and ring connection through the connecting block, but is used when the customer premises equipment is connected in series with a single station, such as an automatic dialer. |
RJ33X | 8P8C
|
This wiring provides a series tip and ring connection of a KTS line ahead of the line circuit because the registered equipment requires CO/PBX ringing and a bridged connection of the A and A1 lead from behind the line circuit. The tip and ring are the only leads opened when the CPE plug is inserted. Typical usage is for customer-provided automatic dialers and call restrictors. |
RJ34X | 8P8C
|
Similar to RJ33X, but all leads are connected behind the line circuit. |
RJ35X | 8P8C
|
This arrangement provides a series tip and ring connection to whatever line has been selected in a key telephone set plus a bridged A and A1 lead. |
RJ38X | 8P4C
|
Similar to RJ31X, with a continuity circuit. If the plug is disconnected from the jack, shorting bars allow the phone circuit to continue to the site phones. Only 4 conductors are used. |
RJ41S | 8P8C , keyed
|
For one data line, universal (fixed loop loss and programmed) |
RJ45S | 8P8C , keyed
|
For one data line, with programming resistor |
RJ48C | 8P4C
|
For four-wire data line (DSX-1) |
RJ48S | 8P4C , keyed
|
For four-wire data line (DDS) |
RJ48X | 8P4C with shorting bar
|
For four-wire data line (DS1) |
RJ49C | 8P8C
|
For ISDN BRI via NT1 |
RJ61X | 8P8C
|
For four telephone lines |
RJ71C | 50-pin | 12-line series connection using 50-pin connector (with bridging adapter) ahead of customer equipment. Mostly used for call sequencer equipment. |
Many of the basic names have suffixes that indicate subtypes:
- C: flush-mount or surface mount
- F: flex-mount
- W: wall-mount
- L: lamp-mount
- S: single-line
- M: multi-line
- X: complex jack
For example, RJ11 comes in two forms: RJ11W is a jack from which a wall telephone can be hung, while RJ11C is a jack designed to have a cord plugged into it. A cord can be plugged into an RJ11W as well.
RJ11, RJ14, RJ25 wiring
All of these registered jacks are described as containing a number of potential contact positions and the actual number of contacts installed within these positions. RJ11, RJ14, and RJ25 all use the same six-position modular connector, thus are physically identical except for the different number of contacts (two, four and six respectively) allowing connections for one, two, or three telephone lines respectively.
Cords connecting to an RJ11 interface require a 6P2C connector. Nevertheless, cords sold as RJ11 often use 6P4C connectors (six position, four conductor) with four wires. Two of the six possible contact positions connect tip and ring, and the other two conductors are unused.
The conductors other than the two central tip and ring conductors are in practice variously used for a second or third telephone line, a ground for selective ringers, low-voltage power for a dial light, or for anti-tinkle circuitry to prevent pulse dialing phones from sounding the bell on other extensions.
Pinout
Observing the male connector from the cable opening, with prong facing downward, the pins are numbered 1–6, left to right:
Position | Pair | T/R | ± | RJ11 | RJ14 | RJ25 | Twisted pair colors | 25-pair colors[A] | Old colors[B] | German colors[C] | Australian colors | Dutch colors[D] | Diagram |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | 3 | T | + | T3 | ![]() white/green |
![]() white/green |
![]() white |
![]() pink |
![]() orange |
![]() 6P6C connector showing the location of pin 1 | |||
2 | 2 | T | + | T2 | T2 | ![]() white/orange |
![]() white/orange |
![]() black |
![]() green |
![]() red |
![]() orange | ||
3 | 1 | R | − | R1 | R1 | R1 | ![]() blue |
![]() blue/white |
![]() red |
![]() white |
![]() blue |
![]() red | |
4 | 1 | T | + | T1 | T1 | T1 | ![]() white/blue |
![]() white/blue |
![]() green |
![]() brown |
![]() white |
![]() blue | |
5 | 2 | R | − | R2 | R2 | ![]() orange |
![]() orange/white |
![]() yellow |
![]() yellow |
![]() black |
![]() white | ||
6 | 3 | R | − | R3 | ![]() green |
![]() green/white |
![]() blue |
![]() gray |
![]() green |
- ^ Established in the 1950s for polyethylene-insulated conductor (PIC) cable.Horn, F. W. (October 1958). "'Even-Count' Cable" (PDF). Bell Laboratories Record. 37 (5): 208–217. Retrieved October 13, 2022.
- ^ While the old solid color code was well established for pair 1 and usually pair 2, there are several conflicting conventions for pair 3 (and sometimes even pair 2). The colors shown above were taken from a vendor of silver satin flat 8-conductor phone cable that claims to be standard. 6-pair solid (old) bellwire cables previously used by the Bell System use white for pair 3 tip but some vendors' cable may substitute orange for white. At least one other vendor of flat 8-conductor cable uses the sequence blue, orange, black, red, green, yellow, brown and white/slate.[citation needed]
- ^ This color scheme originates in the (withdrawn) national standard DIN 47100. The scheme shown here is the correct color code for interfacing with the RJ connector standards.
- ^ "(nl) Support document for the 'PTT norm 88'" (PDF). Watel (in Dutch). p. 8. Archived (PDF) from the original on 2016-10-08.
Provisioning of power
Some telephones such as the Western Electric Princess and Trimline telephone models require additional power (~6 V AC) for operation of the incandescent dial light. This power is delivered to the telephone set from a transformer by the second wire pair (pins 2 and 5) of the 6P4C connector.
RJ21
RJ21 is a registered jack
A cable color scheme, known as
A conventional enumeration of wire color pairs then begins blue (and white), orange (and white), green (and white) and brown (and white), which subsumes a color-coding convention used in cables of 4 or fewer pairs (8 wires or less) with 8P and 6P connectors.
Dual 50-pin ribbon connectors are often used on
RJ45S
![](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b0/RJ45_female_connector.jpg/170px-RJ45_female_connector.jpg)
The RJ45S, an obsolete standard[8] jack once specified for modem or data interfaces, has a slot on one side to allow mating with a special variation of the 8P plug: a mechanically-keyed plug with an extra tab on one side that prevents it from mating with regular (non-keyed) 8P jacks. The visual difference from the more-common 8P female is subtle. The RJ45S keyed 8P modular connector has only pins 5 and 4 wired for tip and ring (respectively) of a single telephone line, and a "programming" resistor connected to pins 7 and 8.[9][10][11]
RJ48
Pin | Pair | Signal | Color |
---|---|---|---|
1 | R | RX ring | ![]() |
2 | T | RX tip | ![]() |
3 | Reserved | ![]() | |
4 | R1 | TX ring | ![]() |
5 | T1 | TX tip | ![]() |
6 | Reserved | ![]() | |
7 | Shield | ![]() | |
8 | Shield | ![]() |
RJ48 is used for T1 and ISDN termination, local-area data channels, and subrate digital services. It uses the eight-position modular connector (8P8C).
RJ48C is commonly used for T1 circuits and uses pin numbers 1, 2, 4 and 5.
RJ48X is a variation that contains shorting blocks in the jack for troubleshooting: With no plug inserted, pins 2 and 5 (the two tip wires) are connected to each other, and likewise 1 and 4 (ring), creating a loopback so that a signal received on one pair is returned on the other. Sometimes this is referred to as a self-looping jack.
RJ48S is typically used for local-area data channels and subrate digital services and carries one line. It accepts a keyed variety of the 8P modular connector.
RJ48 connectors are fastened to shielded twisted pair (STP) cables, not the unshielded twisted-pair (UTP) commonly used in other installations.
RJ61
Pin | Pair | Signal | Color |
---|---|---|---|
1 | 4 | Tip | ![]() |
2 | 3 | Tip | ![]() |
3 | 2 | Tip | ![]() |
4 | 1 | Ring | ![]() |
5 | 1 | Tip | ![]() |
6 | 2 | Ring | ![]() |
7 | 3 | Ring | ![]() |
8 | 4 | Ring | ![]() |
RJ61 is a physical interface that was often used for terminating twisted pair cables. It uses an eight-position, eight-conductor (8P8C) modular connector.
This wiring pattern is for multi-line analog telephone use only; RJ61 is unsuitable for use with high-speed data because the pins for pairs 3 and 4 are too widely spaced for high signaling frequencies.
The flat eight-conductor silver-satin cable conventionally used with four-line analog telephones and RJ61 jacks is also unsuitable for use with high-speed data. Twisted pair cabling is required for data applications. Twisted-pair patch cable typically used with common Ethernet and other data network standards is not compatible with RJ61, because RJ61 pairs 3 and 4 would each be split across two different twisted pairs in the patch cable, causing excessive cross-talk between voice lines 3 and 4, with conversations on each line literally being audible on the other.
With the advent of structured wiring systems and TIA/EIA-568 (now ANSI/TIA-568) conventions, the RJ61 wiring pattern is falling into disuse. The T568A and T568B standards are used in place of RJ61 so that a single wiring standard in a facility can be used for both voice and data.
Similar jacks and unofficial names
The following RJ-style names do not refer to official ACTA types.
The labels RJ9, RJ10, RJ22 are variously used for 4P4C and 4P2C modular connectors, most typically installed on telephone handsets and their cordage. Telephone handsets do not connect directly to the public network, and therefore have no registered jack designation.
RJ45 is often incorrectly used when referring to an
RJ50 is often a 10P10C interface, often used for data applications.
The micro ribbon connector, first made by Amphenol, that is used in the RJ21 interface, has also been used to connect Ethernet ports in bulk from a switch with 50-pin ports to a Cat-5 rated patch panel, or between two patch panels. A cable with a 50-pin connector on one end can support six fully wired 8P8C connectors or Ethernet ports on a patch panel with one spare pair. Alternatively, only the necessary pairs for 10/100 Ethernet can be wired allowing twelve Ethernet ports with a single spare pair.
This connector is also used with spring bail locks for SCSI-1 connections. Some computer printers use a shorter 36-pin version known as a Centronics connector.
The 8P8C modular jack was chosen as a candidate for
See also
- Audio and video interfaces and connectors – generic article
- BS 6312– British equivalent to RJ25
- EtherCON – ruggedized 8P8C Ethernet connector
- Key telephone system
- Modified Modular Jack – a variation used by Digital Equipment Corporation for serial computer connections, and also for CEA-909 antennas.
- Protea (telephone) – South African telephone jack standard
- Telecommunications Industry Association – Standards Developing Organization for ACTA
References
- ^ AT&T, Registration Interface—Selection and General Information, Bell System Practices, Section 463-400-100 Issue 1, May 1976
- ^ a b FCC 47 CFR Part 68 Connection of Terminal Equipment to the Telephone Network Archived 2017-07-05 at the Wayback Machine, Section 68.502 superseded by T1.TR5-1999
- ^ a b c T1.TR5-1999 Archived 2012-03-01 at the Wayback Machine Network and Customer Installation Interface Connector Wiring Configuration Catalog
- ^ a b c "ACTA Documents Main - Administrative Council for Terminal Attachments". www.part68.org. Archived from the original on 10 November 2010. Retrieved 9 May 2018.
- ^ "RJ-11 Definition". Retrieved 24 June 2020.
- ^ a b TIA-968-A Archived 2011-07-23 at the Wayback Machine or tia-eia-is-968 Archived 2011-07-23 at the Wayback Machine documents of FCC Archived 2010-11-21 at the Wayback Machine specifications from the Administrative Council for Terminal Attachments Archived 2016-04-22 at the Wayback Machine, section 6.2 in particular
- ISBN 0-7897-2817-6. Archivedfrom the original on 2014-06-26.
- ^ "The Basics of RJ45, RJ45s, and 8P8C Connectors and Cables". lifewire.com. Retrieved 22 November 2023.
- ^ "RJ45S (Archived copy)". Archived from the original on 2018-05-09. Retrieved 2017-05-22.
- ^ "Modular Jack Wiring". Hamilton Video & Sound Limited. Archived from the original on 2007-10-14. Retrieved 2017-05-21.
- ^ "Modular Wiring Reference". Siemon. Archived from the original on 2010-10-08. Retrieved 2010-10-14.
External links
- RJ glossary
- ANSI/TIA-968-B documents of FCC specifications from the Administrative Council for Terminal Attachments, section 6.2 in particular
- ANSI/TIA-1096-A
- Administrative Council for Terminal Attachments
- Doing your own telephone wiring
- Connecting a second phone line