Mapping between CAT twisted pairs and standard 4-strand telephone wire

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Prepare the Ethernet cable.

The simplest color scheme is used on normal station cable (what your phone tech may call “JK”), which has only two pairs of wire.  The first pair has one green wire (“tip”) and one red wire (“ring”).  The second pair has one black wire (“tip”) and one yellow wire ( “ring”).  For a single phone line, only the green and red pair are normally used.  The black and yellow pair is normally spare and available to install a second phone line.

The other color scheme is somewhat more complicated and is based on a primary color and a secondary color.
The “tip” wire is mostly the secondary color, with marks of the primary color (i.e., white with blue marks).
The “ring” wire is mostly the primary color, with marks of the secondary color (i.e., blue with white marks).
The primary colors are blue, orange, green, brown,, and slate (or gray, if you’re not a phone tech!).
The secondary colors are white, red, black, yellow, and violet (or purple, if you’re not a phone tech!).

Group 1Pair 1-5
Group 2Pair 6-10
Group 3Pair 11-15
Group 4Pair 16-20
Group 5Pair 21-25

Pairs are marked in groups of five.  Each pair within each group uses a different primary color and each group uses a different secondary color.  This allows identification of up to 25 pairs (referred to as a “binder”), which is likely to be the largest cable you’ll encounter in a “residential” environment.  Cables with four pairs are commonly used for many residential and office installations today.

You may find that wire with both color schemes has been used in your installation.
Use the diagram below to translate between the two schemes.

white with blue = green = tip white with orange = black = tip
blue with white = red = ring orange with white = yellow = ring
Pair 1 Color Translation Pair 2 Color Translation


A yellow and blue “jumper” is often used for “cross-connect” between two interface points.


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Pin Functionalities:
1 Data (TX +)
2 Data (TX -)
3 Data (RX +)
4 Ground (-)
5 Ground (-)
6 Data (RX -)
7 Power (+)
8 Power (+)

CAT-5 Ethernet Cable Straight-through Cable Pin Assignments

CAT-5 Ethernet Cable Cross-over Cable Pin Assignments