Q. What is RJ stands for?

RJ stands for Registered Jacks. These are used in telephone and data jack wiring registered with FCC. RJ-11 is a 6-position, 4-conductor jack used in telephone wiring, and RJ-45 is a 8-position, 8-conductor jack used in 10BaseT and 100BaseT Ethernet wiring.




RJ-11 (Telephone) Plug

image of RJ-11 connector

diagram of color wiring

Figure 1

image of wiring of wall jack

Figure 1 is the wiring scheme for the plug side of an RJ-11 connector. The diagram is shown with the “hook clip” on the underside. The typical RJ-11 connector has six terminals. Usually, only the middle four pins are used. The POTS (Plain Old Telephone Service) residential telephone wiring generally contains two pairs of wires – designed for two separate telephone lines. The center pins (Red and Green) contain the first telephone line. Please note that business (digital) phone systems may be wired differently.


 RJ-45 (DATA) Plug Wiring

image of RJ-45 plug and Pin 1 indicated

diagram of the T-568B standard

Figure 2

Figure 2 is the wiring scheme for the plug side of an RJ-45 connector in accordance with T-568B standards. The T-568B standard is the most commonly used. The wiring diagram is shown with the “hook clip” on the underside. The wall jack may be wired in a different sequence because the wires may be crossed inside the jack. When wiring a jack or an RJ-45 plug, remember to keep the “twist” as close as possible to the (jack or plug) receptacle. This will insure compliance with Ethernet wiring standards.

Networking Tools:

Bulk Ethernet Cable – Category 5e or CAT5e

(You may also use Category 6 or CAT6 cabling which has higher performance specifications and is about 20% more expensive than CAT5.)

Bulk RJ45 Crimpable Connectors for CAT-5e
Bulk RJ45 Crimpable Connectors for CAT-6

RJ-45 & RJ-11 Crimping too

This simple testing technique is a great way to check the connection quality of RJ45 terminations on new CAT5, CAT5e and CAT6 LAN cables, and can also be helpful in troubleshooting the data transmission problems in existing network cabling.