I should probably start a new thread for this board thing, but thought I'd follow up I'm working on a board revision that can handle rotary too. A few people have asked for this; some on the web, and one request from ChrisRR.

Detecting rotary is a trivial circuit (a single optocoupler, the same as the ones I use for ring and line detect), and with a PIC chip it should be pretty easy to count the pulses, and from that determine which extension to buzz. I imagine I should buzz for about a second. (With DTMF it buzzes for as long as the touch-tone button is held down, but that doesn't work with rotary, so I figure I'll need to set a fixed buzzing time)

That board is slated to be Revision "F", if I end up making it.

Still in R&D on that one, but had good luck analyzing a very clean, almost like new 565HKM phone (that smells like hair spray for some reason) I just acquired off Ebay to work with. The rotary seems to generate pulses that are around 65 msecs long, with 20 msecs spacing, or around 11.7 IPS, if I measured correctly.

Is the spec for adjusting the rotary mechanism documented in the BSPs somewhere? I found a wikipedia page that went into this detail saying, more or less, phones in the US were adjusted to be between 9.5 and 10.5 IPS, which is a little slower than my phone. Perhaps unadjusted phones "wear out" and go faster? Or maybe those numbers are old, and newer phones were adjusted to go faster.

The page also went on to say switching equipment could handle a range of between 8 and 12 IPS, and that operator rotary dials could go as fast as 20 IPS.

I need to know all this to implement into the firmware, so that it can tell the difference between dialing and other non-dial generated "noise".

If anyone can add clarity to this, let me know. I'll dig around in the BSPs for the 565HKM, but I'm not sure the documents I have cover this subject, especially on the exchange end of things. I guess docs for the strowger switches might cover max/min dialing speeds, as I take it until electronics came along, those were the devices that were direct-driven by the rotary impulses, so the pulses had to be slow enough to drive the solenoid mechanisms in those strowger switches.