RJ11 VS RJ45: What Is The Difference

 RJ11 and RJ45 are two common types of the modular connectors that are used in voice and data communications. Though these two connectors have a similar look, they both have different wiring arrangements and serve different purposes. In this article we will go over the differences between the RJ11 and the RJ45 and their applications.

What is Registered Jack?

To begin, lets discuss what the letters RJ stand for.  The acronym “RJ” stands for Registered Jack. A Registered Jack is a male cable connector that plugs into the female socket on a device. These jacks serve as a standardized telecommunications network interface that connects voice or data services to a phone system, central router or modem.

What Is RJ11?

An RJ11 is a connector often referred to as a phone jack. This connector is square and shorter than an RJ45.  It has six positions and four wires (6P4C) that can make two connections at a time with one pair connected to the communication line. The RJ11 supports bandwidth speeds of up to 24Mbps. 

 What Is RJ11 Used For?

The RJ11 is used to terminate telephone wiring for voice applications such as telephone lines, ADSL/VDSL lines, Modem cables, and specifically PSTN networks. It is most commonly used for plugging a telephone into the wall jack and the handset of the telephone.

 RJ11 Color Code

The RJ11 connector has a standard color code pinout which is used to help identify each conductor within the connector. A traditional telephone system will use four conductors which are typically colored red, green, black and yellow. The red and green conductors are for transmitting voice signal, while the black and yellow conductors are for signaling purposes. 

What is RJ45?

An RJ45 is a connector often referred to as a modular plug. It is rectangular in shape and longer than the RJ11. It has eight positions and eight wires (8P8C). The RJ45 can support bandwidth speeds of up 10Gbps.

 What is RJ45 Used For?

The RJ45 is used to terminate Ethernet cables for both telecom and data networks. These cables are used to connect various devices in cable network such as computers, cables, routers, switches, hubs and more.

 RJ45 Color Code

The RJ45 has two standard color code pinouts, T568A and T568B used in straight through and crossover cables. These two standards are identified by the color-coding arrangement of the eight wires necessary when attaching the connectors to a cable. The only difference between the two is the wiring position of the green and orange pairs but both are acceptable.

RJ11 vs RJ45 Comparison

 RJ11 and RJ45 are two common types of the modular connectors. The key difference is in the number of conductors and their intended applications. RJ45 is used for Ethernet cables while RJ11 is for telephone lines.

RJ11 vs RJ45 Comparison Chart:

Configuration6P4C (6 positions, 4 conductors)8P8C (8 positions, 8 conductors)
Bandwidth24 Mbpsup to 40 Gbps on Cat8
         up to 10 Gbps on cat7 /cat6a
        up to 1 Gbps on cat6 / cat5e
Shape and sizeCompact, square-shapedLonger, more rectangular
UsagePhones, ADSL lines, modem cables. Mostly used for voice applications.Computer networking. Ethernet or connecting cable modems with Wi-Fi routers.

Can You Use RJ11 and RJ45 Connectors Interchangeably?

The short answer is No. Even though you can easily plug an RJ11 into an RJ45 jack or Ethernet port, we do not recommend to do so. Plugging an RJ11 connector into an RJ45 port can potentially  damage it and will result  in a poor connection.

On the other hand, the RJ45 cannot be used interchangeably with the RJ11 port for three important reasons.

·      First, the connectors are difference sizes and the port can become damaged if you try to insert it.

·      Second, the RJ11 is for telephone lines and connections, whereas the RJ45 connects Ethernet cables to computers and other devices.

·      Third, if there is a power-outage, power delivery is still being supplied through the wire by the telephone company into the handset which can damage the port.

Can RJ11 cables be used for Internet?

No. RJ11 cables do not have enough pins to support the data speeds needed for Ethernet.