Colour coding doesn't mean much on a long D-side rural run of cable. For example, the cable leaving the Cabinet will probably be a 50/100pr .... this in turn will slowly become a lower-capacity cable (1/2/5/7/10/15/20/30pr) as the distance increases and pairs are 'dropped off' at various other DP's.
Therefore, in essence, 'your' circuit could be leaving the Cabinet on a green/white pair of wires and arrive at the premises on a slate/red pair.
So, there are basically two methods we would deploy to identify the End Users pair. One would be to apply a manual tone generator (Otherwise known as an oscillator), or we can apply an 'Auto-tone' from our work i-Phones by using the 17070 facility, which recognises the task we are on and offers up a suite of applications we can use such as remove/apply voltage, remote emulation scripted tests, auto-tones etc ....
With the tone applied, we then identify the circuit we are working on using a probe that gives an audible identification by getting louder the nearer the pair you are trying to isolate. Probes are more commonly referred to as 'Swaffers' or 'Wands' .... depending on which part of the country you are working in.