Also, if your wiring is color-coded with blue, orange, green and brown pairings, then the understanding you need to have, first, is that the primary pair is terminated in the center, that is, pins 2 & 3. The secondary pair goes on the outside pins, pins 1 & 4.
With the USOC color-coding scheme, (green/red and black/yellow) the primary pair is green/red and the secondary pair is black/yellow.
These pairs have a "tip" and a "ring" conductor. The first conductor of the pair is the tip conductor, i.e., the green conductor or the black conductor.
With the "568" color-coding standard, the primary pair is the blue pair; orange is the secondary pair. Usually, the polarity of each pair (i.e., whether you have terminated it as green/red or red/green) does not matter these days.
Here the tip conductor is the white conductor of the pair, i.e., the conductor with the mostly white color and a trace color stripe that corresponds to the color of the pair. That would be the white w/blue tracer of the blue pair, the white w/orange tracer for the orange pair, etc.
Be aware however, that the source end of the cable may have your circuit of interest connected to any (!) of the available pairs.
Yours,
Mike