A bit late to the party , but for future use, here's a copy of N diagram 432 ( GPO diagrams for phones always added 100 to the phone title). ( worth keeping in mind if you end up with other old phones). I never really worked on them as in my subs app days, we just swapped them out for a 700/740 series.
http://www.samhallas.co.uk/repositor.../0000/N432.pdf