What Bill said. It's a standard 20 button 1A2 set. It needed all 50 pairs to provide 1A2 functionality on 19 lines. It used 3 pairs for the first line, 2.5 pairs for the next 18 and 1 pair for the ringer =49, leaving exactly 1 pair spare for the Intercom buzzer.

The phones worked very well and required very little maintenance. Every once in a while you would have to change a lamp or a coil cord and every once in a long while a dial.

The 20 button model had the same footprint as the 10 button unit and phones could be upgraded from 10 to 20 by adding another keystrip and cable and changing the faceplate - something that we did more often then you might think.

I probably installed hundreds of them in my relatively short career as a 1A2 installer.

Sam

"Where are we going and why are we in this hand basket?"