Anyway, I believe panel switching and certainly crossbar and ESS could
> and would accept 20 pulses per second. Way back in HS a kid figured
> out on his phone dial an adjustment to make it 20 p/s and it worked
> (on either #1 xbar or panel). PBX switchboards had 20 p/s dials.
As I recall, operators had dials that did 20 pps.