RJ9 vs RJ12: Difference and Comparison

A registered jack (RJ) is a standard network interface used in network cabling, wiring, and jack design.

The essential capacity of registered jacks is to interface distinctive information hardware and media transmission gadgets with administrations regularly given by phone trades or significant distance transporters.

RJ9 and RJ12 are crimped gold pin connectors in telecoms, networking, and low-voltage lighting applications. The difference is determined by the number of contacts on the connector and the actual number of connections.

Since there are more sites, the connector is larger. The specification only defines the cable pattern of a connector, not its sex or geometry.


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The name “Jack,” even though the standard doesn’t recognize the sex of the connector, applies to the female connector. These connectors are frequently called “measured connectors.”

They have made the telephone network more particular in the good old days. The RJ determination is generally indicated for the wiring of media communications organizations.

The RJ standard link-designed connectors are alluded to as RJ connectors and can be utilized in people.

Key Takeaways

  1. RJ9 and RJ12 are phone connectors, with RJ9 being smaller than RJ12.
  2. RJ9 connectors have four or six pins, while RJ12 connectors have six or eight pins.
  3. While both connectors connect phones and other telecommunications devices, RJ12 connectors are more commonly used for larger phones and phone systems. In comparison, RJ9 connectors are used for smaller phones and headsets.

RJ9 vs RJ12

RJ9 or registered jack 9 uses a 4P4C connector to support up to 4 wires. It is a plastic, rectangular device ideal for connecting telephone handset cables. RJ12 or registered jack 12 uses a 6P6C configuration which can connect up to 6 wires simultaneously. It is a compact-shaped device that is used to establish a single telephone connection.

RJ9 vs RJ12

The RJ9 has a marginally unexpected shape in comparison to the RJ12. Although it has a rectangular shape, it is smaller than the RJ12.

It’s made of plastic and transparent because you can see how the wires are connected. The RJ9 only has one configuration type, the 4P4C attachment type, which implies four locations and four connection points.

It allows it to work with telephone handset cables.

For a centralized telephone network in offices, RJ12 is a communication jack that connects a central telephone grid with single telephone lines using a line circuit that uses specialized RJ12 6-flat ribbon standard cables.

The RJ12 norm is also used in a variety of other applications. The additional two connectors will be used for keyed telephone systems and PBXs.

As a result, RJ12 is not commonly available, and only those with previous experience dealing with large corporation telecommunications networks are familiar with it.

Comparison Table

Parameters of comparisonRJ9RJ12
Full-FormRegistered Jack 9Registered Jack 12
Connector4P4C = 4 Position 4 Conductor6P6C = 6 Position 6 Conductor
PurposeRJ9 is regularly utilized as a cable for telephone handsets.RJ12 is commonly used in system phones.
Physical CharacteristicsRJ9 is rectangular.RJ12 is compact and square-shaped.
DefinitionRj9 is a connector ideal for use in connecting telephone handset cables.RJ12 is a line circuit that associates a focal phone framework to single phone lines through a connection jack

What is RJ9?

There is a ton of disarray around this connector structure. On occasion, it is alluded to as the Rj10, and it might likewise be recognized as the Rj22.

This is because every one of these connector types has comparative measurements and designs.

This connector is more rectangular than it is square. Its width is 7.6mm, making it somewhat more modest than the Rj12 connector. It has a practically comparable form, however.

It is produced using unbending and robust plastic that is additionally clear. This plastic uncovers the association of wires.

This association has a 4P4C arrangement, like the Rj10 and Rj22, which explains that they seem similar. Its design implies that it has four positions and four association focuses.

It is ideal for interfacing phone handset links. It has composite pins that are made of copper. The top coat of these pins is treated with an amalgam of 30 microns of gold and 30 microns of nickel.

It forestalls the copper pins from rusting and gives them a more stylishly engaging look.


What is RJ12?

The full version of Rj12 is Registered Jack 12. A jack links a central telephone grid to individual telephone lines through a line circuit. It’s a male connector that lone joins a female Rj12 jack to make an association.

A 6P6C connector is used on the Rj12. It has six link slots, all of which are used for contact. For Rj12 connectors, specific RJ12 6-level trim standard connections are used.

This link is comprised of six dainty copper links that convey and get electrical messages.

Both six copper wires in this regular ribbon cable are colour-coded. The shades used are white, black, red, green, purple, and blue.

The Rj12 is unlike any other wearing device in that it is unique and complicated. To make the copper-wearing device work, the cable technician must put it in the proper order.

When numerous corporate offices needed a consolidated telephone network for private use in the 1980s, the Rj12 connector became common.

This connector makes setting up a phone-based neighbourhood in the working environment simple. Numerous workplaces use this connector to set their radio framework, especially in this cutting-edge period.

Main Differences Between RJ9 and RJ12

  1. RJ9 is rectangular, whereas RJ12 is squared in shape.
  2. RJ9 is used for telephone handset cables, whereas RJ12 is used in the system phones.
  3. RJ9 has a 4P4C connector, whereas RJ12 has a 6P6C connector.
  4. RJ9 is the abbreviation for Registered Jack 9. RJ12, on the other hand, is an abbreviation for Registered Jack 12.
  5. RJ9 is visually pleasing, whereas RJ12 is compact.
  1. https://ieeexplore.ieee.org/abstract/document/6843694/
  2. https://currentprotocols.onlinelibrary.wiley.com/doi/abs/10.1002/cpmo.81
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