Desired features for Port-O-Rotary v2:

  • Pulse decoder - Done!

  • Ringer driver - Needs work.

  • On-hook detection - Done!
  • Battery charger - Done! (Built into the FONA)
  • Dial tone injection (350 and 440 Hz) - Done! (Built into the FONA)
  • Dialup modem support - sort of. Connection quality is very bad.

Source code: github.com/osresearch/rotary

Circuit board in the ITT 500 series phone:

E2 A = bell gray/red E1 G = RJ45 yellow
F = dial blue K C = bell gray L2 = RJ45 red, bell red, hook relay
GN = dial white, RJ45 white B = RJ22 black L1 = RJ45 green, hook relay gray/green, bell black
RR = dial green
R = RJ22 red and white, dial white, relay

The rotary dial has two switches: the white one is open at rest and closed when the dial is disturbed from the rest position, the blue/green is normally closed, but opens when the rotor crosses a number.

2017 Retrocomputing

Last update: November 8, 2020