Update: I switched to a different ATA for the Commodore modem (it just has one port) which lets me disable echo suppression and now the modem handshake proceeds to a second tone. It still doesn't connect, but now both modems beep twice at two different pitches. For both modems, the first beep is at ~2100Hz and the second is at ~1650Hz, and the second beep continues until I end the call.
I've recorded the handshake attempts if folks are curious.
Here's the C64 side of the handshake from dial tone to the two beeps: https://mega.nz/file/19twTD6b#NUXKBaOJBxzejLFIUDZn-GaSiBHwrUmZcuS4YlENeb0
And here's the Hayes modem side, from the click where it answers the call to the beeps:
https://mega.nz/file/0hU11ajT#8ZEga0WNuI250s53o2Rv-GXzD52c1_wAhcYh1HJlq0o
I've also tried using the Common Sense terminal program instead of Novaterm, but I can't get it to auto dial - pressing Commodore+A has no effect. All the other features I've tried have worked, and when I accidentally bumped the modem it caused a bunch of text to appear in the terminal, and when I called it it printed "RING". I might still be able to use it but provide the touch tones from elsewhere. I've got an Android app that generates touch tones, and I've plugged my phone's headphone jack into the "audio in" port on the modem which works pretty well.
My new ATA should arrive tomorrow so I'll be able to turn off echo cancelation on the Hayes side of the connection.
#Commodore #Commodore64 #C64 #RetroComputing