gridbugsFeb 4

Trying to get my #Commodore 300 modem to connect to my Hayes-compatible modem over VOIP. Generating touch tones with the SID chip wasn't working (it played the sounds but no response from ATA) nor was pulse dialling, but I found I can attach a phone to the Commodore modem and use it to start a call and then "hang up" in the Commodore terminal software which seems to cause the Commodore to take over the call (I hear the ring tone through the modem rather than the phone), then answer the call by sending an ATA command to the Hayes-compatible modem. Both modems then beep at the same pitch which sounds like the start of a handshake, but after a second or so the Commodore modem goes quiet and the Hayes modem keeps beeping, but they don't connect.

I'm using G.711 as my VOIP codec and I've configured the Hayes modem to use 300 baud. I suspect my ATA is filtering the audio as though it was voice, but it doesn't have settings to turn this off (it's just my router which happens to contain a 2-port ATA). I've ordered a second-hand ATA which looks like it will be more configurable (a Cisco ATA191).

Also considering making an RJ11 cross-over cable to test a direct connection between the modems.

Does it sound like I'm on the right track? Looking for advice from more seasoned #RetroComputing folks about what to try next.

#Commodore64

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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

402 KB file on MEGA

Feb 5 at 3:38pmWeb