Ethernet Wiring (8P8C, often incorrectly called RJ45)

For a normal cable you can use either T568A or T568B as long as you use
the same scheme on both ends. For a cross-over cable use one of each.
1 White/Green
2 Green
3 White/Orange
4 Blue
5 White/Blue
6 Orange
7 White-Brown
8 Brown
EIA/TIA 568A Color Scheme

EIA/TIA 568B Color Scheme

POTS (Plain Old Telephone Service) RJ11, RJ14, RJ25

Holding the connector in your hand tab side down with the cable opening toward you, the pins are numbered 1-6, left to right.

position RJ25 pin RJ14 pin RJ11 pin Pair T/R Cat 5e/6 colors Old colors
1 1     3 T+ white/green orange
2 2 1   2 T+ white/orange black
3 3 2 1 1 R- blue red
4 4 3 2 1 T+ white/blue green
5 5 4   2 R- orange yellow
6 6     3 R- green blue

While the old solid color code was well established for pairs 1 and 2, there are several conflicting conventions for pair 3. The colors shown above were taken from a vendor of "silver satin" flat 8-conductor phone cable that claims to be standard. Other 6 pair solid (old) bellwire cables may substitute white for orange. At least one other vendor of flat 8-conductor cable uses the sequence blue, orange, black, red, green, yellow, brown and white/slate.

In modern structured wiring Cat5e or Cat6 is commonly used in homes and buildings. The Cat 5e and Cat 6 data lines are often used for both voice or data. The color codes above are the standard and defined within wiring guides.