Editing Registered jack (section)

==Types{{anchor|RJ12|RJ41|RJ45}}==
[[File:Conector RJ11.jpg|thumb|6P4C crimp-on style connector, commonly used for RJ11 and unpowered RJ14]]

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 [[Modular connector#8P8C|''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{{dash}}''never used for RJ45S''{{dash}}is used in Ethernet networks, and the connector is often, however improperly, referred to as ''RJ45'' in this context.

{| class="wikitable"
|+ Officially recognized types of registered jacks
|-
! 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). In computers, it is often used for [[dial-up internet]] access.<ref>{{cite book | url=https://books.google.com/books?id=GZFxBgAAQBAJ&dq=rj-11+dial+up&pg=PA67 | isbn=978-1-118-96769-0 | title=The Internet for Dummies | date=2 March 2015 | publisher=John Wiley & Sons }}</ref>
|-
| 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
| [[8P8C|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
| [[8P8C|8P4C]]
| For four-wire data line (DSX-1)
|-
| RJ48S
| [[8P8C|8P4C]], keyed
| For four-wire data line (DDS)
|-
| RJ48X
| [[8P8C|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.