Phone jack wire color codes

Jacks and plugs are wired to conform to Uniform Service Ordering Code ("USOC") numbers, originally developed by the Bell System, and endorsed by the FCC. One specific piece of hardware can be wired in different ways, and have different USOC numbers. USOC has become an acronym, pronounced "you-sock," and jack wiring schemes are referred to as "USOC codes."

The 8-position modular jack (above) is commonly and incorrectly referred to as “RJ45”. The 6-position modular jack is commonly referred to as RJ11, which may or may not be correct. Using RJ terms often leads to confusion since the RJ designations refer to very specific USOC wiring configurations. The designation ‘RJ’ means Registered Jack, and should be used only for jacks that are connected directly to phone company circuits.

Each of the basic jack styles can be wired for different RJ configurations. For example, the 6-position jack can be wired as an RJ11C (1-pair), RJ14C (2-pair), or RJ25C (3-pair) configuration. An 8-position jack can be wired for configurations such as RJ61C (4-pair) and RJ48C. The keyed 8-position jack can be wired for RJ45S, RJ46S, and RJ47S. The fourth modular jack style is a modified version of the 6-position jack (modified modular jack or MMJ). It was designed by Digital Equipment Corporation (DEC) along with the modified modular plug (MMP) to eliminate the possibility of connecting DEC data equipment to voice lines and vice versa. (This paragraph is based on info from Siemon.)

In the diagrams below, you are looking into the opening of the jack. Internal wiring in the jack may have different colors from the wiring that goes to the jack.

6 Positions
2 or 4 Wires
1 or 2 Lines
RJ11 or RJ14
Jack►
 
USOC
RJ11
USOC
RJ14
Positions▼      
2 wht/org
3 blue/wht blue/wht
4 wht/blue wht/blue
5 org/wht

6 Positions
6 Wires
3 Lines
RJ25
Jack►
 
USOC
RJ25
Positions▼  
1 wht/grn
2 wht/org
3 blue/wht
4 wht/blue
5 org/wht
6 grn/wht

Wires inside most phone jacks are usually solid- colored, not striped.

For many years, it was customary to use "quad" solid- color wire, that matched the wires inside a jack.

If you are installing a new jack, it's best to use modern "twisted-pair" wire, with stripes.


8 Positions
4 or 8 Wires
4 Lines
RJ61 & others
Jack►
 
USOC
RJ61
T568A T568B
(AT&T)
Positions▼      
1 wht/brn wht/grn wht/org
2 wht/grn grn/wht org/wht
3 wht/org wht/org wht/grn
4 blue/wht blue/wht blue/wht
5 wht/blue wht/blue wht/blue
6 org/wht org/wht grn/wht
7 grn/wht wht/brn wht/brn
8 brn/wht brn/wht brn/wht
 
 
►Note: If you are going to re-use jacks previously installed for a Merlin or other ATT/Lucent/Avaya phone system that uses the T568B wiring scheme, for a phone that needs standard "USOC" wiring, you will either have to re-arrange the wires inside the jack, or connect the circuit that would normally go on the white/orange wire pair, to the white/green pair.
►Note: 8-position jacks and plugs used in Local Area Networks ("LANs") are commonly referred to as RJ45. This is incorrect, because RJ designations apply only to jacks connected to phone company circuits, not PCs or network hubs.

The black diagrams and some of the info above came from Hubbell. We thank them.