Ed,
Kadoos... on the red/white pair.
and yes you are correct about the relays on the interruptor. They had a distinct pattern, you could identify that system unseen from 20 feet away. intercoms were determined by picking tens from one lead and ones on the other.
the tie system even had different taps on the lamp power resistors so that if you added more extensions and the lamps were starting to dim, you just changed the wire tap setting to make them brighter.
do you think it's time to start telling the young pups about frequency selective ringing, party lines and 4 digit dialing?
Tj
