I know they're polarity sensitive, I have dozens of phones with polarity sensitive dials. Not one of them has a PG on it. One of the ways Bell took advantage of the dials being polarity sensitive was to reverse the polarity on a line that was using TT dialing when they weren't paying for it.
EDIT:
As a general rule, bell did NOT install PG's into normal service for this reason. There were some applications that required one to be installed, but it was uncommon. Towards the end of the bell system dials came with the PG built in, but from the 60's until the early 80's they didn't.
Last edited by ChrisRR; 11/03/18 05:38 PM.
