here are two accepted standards for 8-wire data network jacks (commonly and incorrectly called "RJ-45.")
ANSI/TIA/EIA-568-B "Commercial Building Telecommunications Cabling Standard" lists both wiring configurations. T568B is the most prevalent for commercial installations, and was used by AT&T for the original Merlin phone systems. To help you remember, associate "B" with "Bell."
ANSI/TIA/EIA-570-B "Residential Telecommunications Cabling Standards" recommends T568A
•If the installation is residential, choose T568A unless other conditions apply (see below). The two inner pairs of 568A are wired the same as a two-line phone jack.
•If there is pre-existing voice/data wiring (remodel, moves, adds, changes), duplicate this wiring scheme on any new connection.
•If project specifications are available, use the specified wiring configuration.
•If components used within the project are internally wired for either T568A or T568B, use that wiring scheme.
•Make sure both ends of a cable are wired the same way.
Pin # T568B T568A
1 White/Orange White/Green
2 Orange Green
3 White/Green White/Orange
4 Blue Blue
5 White/Blue White/Blue
6 Green Orange
7 White/Brown White/Brown
8 Brown Brown