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Differences Between the RJ45 and RJ11

Author:danny / time:2018-04-11 / The number of clicks:2116

The Registered Jack 45, or RJ45, cable is modular connector commonly used in homes and offices for Ethernet connections and computer networks. It is often confused with the RJ11, which is the most commonly used connector for telephone lines. Because of similarities in their appearance, these two connectors are often used interchangeably. But RJ45 connector is very much different from the smaller RJ11. This article will discuss the difference between the two connectors in terms of appearance, structure, wiring scheme, and applications.



Although the two connectors may look alike at first glance, the RJ45 and RJ11 are actually physically different from each other.


Close examination will reveal that the RJ45 is actually a little bit wider and longer than the RJ11. This is because the former accommodates more wires. The difference may be considered negligible, though, which is why most people sometimes make the mistake of plugging in an RJ11 cable into an RJ45 socket. While this is physically possible, it should be avoided to prevent damage to the RJ45 socket.



Differences in structure are more evident.


The RJ45 is a twisted-pair modular connector that has eight wires and eight slots inside. This structure is called eight-position, eight-contact (8P8C).The wires are spaced one millimeter apart and are each a different color, with four wires in solid color and the other four in striped color.


The RJ11, on the other hand, is a six-position, two contact (6P2C) connector. This means that it uses six positions as opposed to the RJ45’s eight, and only two conductors, versus the RJ45’s eight. Out of the six positions, only two to four are used. Using only two out of six positions makes it capable of being wired with a 6P2C type of modular jack.


Wiring Scheme

There are also significant differences in the wiring schemes of these two types of connectors.


As discussed earlier, the RJ11 connector has six positions, with only up to four middles positions in use. Because of this wiring scheme, the RJ11 is commonly used in single-line plain old telephone service (POTS) residential handset jacks. This wiring scheme usually has two pairs of wires that can accommodate connections for two telephone lines, with the red and green pins (the ones at the center) being used for the first telephone line.


Meanwhile, the RJ45 connector connectorfeatures two different wiring schemes—the T568A and T568B. These are useful in creating two types of cable systems—the straight-through and cross-over cable systems.


Straight-through cable system. Sometimes called “patch cable,” this is used to connect to a switch. In this system, the cable is wired the same at both ends. This means that either the T568A or T568B is used on both ends of the cable. It is called a “straight-through” scheme because no pin assignments have been swapped.


Cross-over cable system. The cross-over cable system is used for connecting computers to one another without a switch. Considered the more common pinout type for the RJ45 connector, it uses one T568A on one end and one T568B on another.



The most significant difference between the two lies in how and where each one is used.


The RJ11 connector, given its structure and wiring scheme, is widely used for ADSL, modem cables, telephone lines, selective ringers, and anti-tinkle circuitry. The RJ45, however, is used with Ethernet cables when networking computers.



Knowing these major differences between the RJ45 connector and the RJ11 connector will help you better understand what type of connector to use in your home or office. Remember to take these points into consideration the next time you set up your computer.