🚀 go-pugleaf

A 5 button Key-System is pretty easy to wire.  The cable has 50 wires,
or rather 25 pairs.  Each pair has 2 colors, a primary color, and a
secondary color.  The primary colors are Blu, Orn, Grn, Brn, and Slt, 
(Slt is slate, or gray).  The secondary colors are Whi, Red, Blk, Yel,
and Vio.  The first wire in a pair is a wire of a primary color with
stripes of a secondary color.  The second wire in a pair is a wire of
the secondary color of the first wire, with stripes of the primary color.
Ex. Blu-Wht and Wht-Blu is a pair.  A blue wire with white stripes, and
a white wire with blue stripes.

Going down the long 50 pin connector, the first pair is on pins 1 and 26.
(the Blu-Wht pair)  The second is on pins 2 and 27, (the Orn-Wht pair),
The third pair on pins 3 and 28, (the Grn-Wht pair).  On the 6th pair,
we go to the next secondary color and cycle the primarys again, so the 6th
pair is on pins 6 and 31, (The Blu-Red pair).

Not everything in key systems are done in pairs, but for the most part,
pairs will do.  Things also vary slightly from manufacturer to manufacturer.
But, I have seen the Tip-Ring pairs pretty consistently in the same place.

Each line takes up 3 pairs:
  The Ring-Tip pair
  The A-lead pair, (used for putting the line on hold)
  The Lamp pair, (Power for the lamp associated with each line)

As one might expect:
  Line  Pairs  R-T      A-Leads  Lamp
  ----  -----  -------  -------  -------
  1     1-3    Blu-Wht  Orn-Wht  Grn-Wht 
  2     4-6    Brn-Wht  Slt-Wht  Blu-Red 
  3     7-9    Orn-Red  Grn-Red  Brn-Red 
  4     10-12  Slt-Red  Blu-Blk  Orn-Blk 
  5     13-15  Grn-Blk  Brn-Blk  Slt-Blk 

The ringing to the phone is usually provided on the 20th pair, (Slt-Yel pair).

The entire system is essentially wired in parrallel, unless you have a
system with different lines on different phones, or an intercom system
which lets you dial an individual station, or other strangness.

Hope this helps.

-Mike Grant