RJ12 Vs. RJ11 Vs. RJ45 Connector: What Is The Difference?


Our lives depend heavily on cables and connectors. Do you know what makes RJ12, RJ11, and RJ45 different?

RJ12 is a 6P6C wiring standard. This indicates that all six wires are terminated in the connector and take up all of the slots.

The remaining two slots in RJ11‘s 6P4C wiring standard are no longer in use, and only four wires are connected to them.

As a result, even though they may appear to be identical, cables used for RJ11 may not be appropriate for RJ12, so you should pay close attention to the cables you are using.

Keep reading and explore more about these 3 types and what distinguishes them.

What Is RJ11?

RJ11 is a registered jack 11 in its entirety. It is a jack for connections that bridges two telephone lines together. Analog systems use the RJ11 connection jack.

Low voltage electrical signals are transmitted through this connection jack. Two-way connections use RJ11 technology. Through it, low voltage electrical signals can be sent and received.

There is a 6P2C connector on this jack. For wearing connections, it has six slots. All of this jack’s slots, however, are not utilized for wiring.

Only two of the middle slots are typically utilized for bridging connections. When sending low voltage power to the telephone’s indicator lamp, six P4C slots are used.

To transform the telecommunications system, the RJ11 jack was created in the 1970s. It is a male component of the connection system.

the jack necessary to connect the RJ11 compatible female section. This jack made it simple to connect two lines. The RJ11 connector jack is not compatible with all cables.

Only flat stain cable with 2-4 copper wire can connect to an RJ11 connector, and a crimper tool is needed to create a secure connection.

All global telecommunications providers accepted the RJ11 jack. The global telecommunication connector system was able to be standardized thanks to the jack.

All wired phones and dial-up modems still use this connector in the digital age.

Related Reading: When would you typically use an RJ11 connector?

What Is RJ12?

RJ12 stands for registered jack 12 in its entirety. Through a line circuit, it is a connection jack that connects a central telephone system to individual telephone lines. It is a male plug that can only make a connection with an RJ12 female jack.

A 6P6C connector is used by the RJ12. The six connection-wearing slots on it are all utilized for communication. RJ12 connectors are connected by means of specialized RJ12 6-flat ribbon standard cables.

Electrical signals are sent and received through the six thin copper cables that make up this cable.

Each of the six copper wires in this ribbon standard cable has a different color. White, black, red, green, yellow, and blue are some examples of these colors. The RJ12 is entirely unique and complex in comparison to other wearing systems.

To make the copper-wearing system work, the cable technician must arrange the components in the proper sequence.

When various corporate offices needed a centralized telephone network for personal use in the 1980s, the RJ12 connector became widely used.

What Is RJ45?

RJ45 connectors are frequently used for Ethernet networking. It resembles a telephone jack in appearance but has a wider surface.

RJ45 connectors are used to connect the wire cables, so they are commonly used to refer to all Ethernet cables by this name. It has eight pins in total. In other words, there are 8 different wires.

If a person closely examines any Ethernet cable, they will notice this. Four of these eight wires are solid colors, and the remaining four are stripped.

Generally, Cat 5 and Cat 6 cables are connected using this. The RJ45 connector has an eight wire capacity, which makes it both internally and externally robust and durable.

To keep the wire from rusting from outside influences, it has copper pins with a gold coating. The ability to transmit extremely high energy at extremely high speeds is the RJ45 connector’s key characteristic.


Differences Between RJ11 And RJ12

  1. RJ12 is a connection jack that joins a central telephone system with single telephone lines through a line circuit, while RJ11 is a connection jack that bridges a connection for a single telephone line.
  2. RJ11 is short for registered jack 11. Alternatively, registered jack 12 is the full form of RJ12.
  3. For a typical telephone connection, RJ11 typically employs a 6P2C connector. It only employs a 6P4C connector when sending low voltage power to the telephone’s indicator lamp. However, the 6P6C connector is always used with the RJ12 jack.
  4. Flat stain cable with two delicate copper wires is used with the RJ11 jack. However, the RJ12 jack, which has six thin, color-coded copper wires, requires special RJ12 6-flat ribbon standard cables.
  5. Typical home wire telephone and modem connections use RJ11 jacks. However, RJ12 jacks are only employed in offices for centralized telephone networks.

Differences Between RJ12 And RJ45

  1. In contrast to the square shape of the RJ45 connector, the RJ12 connector is rectangular in shape.
  2. In contrast to the RJ45, which has eight connections and eight positions, the RJ12 is a connector with six connectors and six positions.
  3. The RJ12 connector is primarily used to connect telephone lines, whereas the RJ45 connector is primarily used to wire numerous networks.
  4. The major lines are connected by the RJ12 using Cat 3 or Cat 5 wiring, whereas the RJ45 uses Cat 5 or Cat 6 wiring.
  5. In contrast to the RJ45, which has eight slots, the RJ12 has six slots.


RJ11 had a brilliantly straightforward design. All phone sockets allowed for a simple plug-in. Additionally, it had a very durable design for standard telephones and modems found in homes.

It connects using a standard flat stain cable. Two thin copper wires are used in this cable to facilitate two-way analog communication.

RJ12’s design is incredibly challenging, though. Specialized RJ12 6-flat ribbon standard cables are required for this jack.

However, the RJ45 is typically described as being a little bit wider than the RJ12, making it more durable and able to transmit powerful radiation.