gridbugs

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

Feb 4 at 1:46pmWeb
Show threadgridbugsFeb 5

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

Show threadNRoach44Feb 4

@gridbugs off the top of my head,

* turn off fax awareness
* turn off echo cancellation
* turn off anything that sounds like dynamic jitter compensation; set it to manual and the highest setting, if possible

I can somewhat reliably get 28.8k on a SPA8000 -> Cisco 3745 and those were the key settings.

I would also check that your phone line settings are right (regional variations like dial tone) but not sure if those are your problem.

Show threadpaulrickardsFeb 4
@gridbugs I saved this slide from a Jawncon presentation on modems and VoIP that may help.
Show threadvga256Feb 4

@gridbugs you've done everything right so far in my books. while it could be overly aggressive voip compression/filtering, it wouldn't be my first suspect. anything under 9600 baud is normally very easy to handshake at over G7.11. my money is on a problem with the commodore (or 300 modem) itself.
which terminal program are you using? commodore's Common Sense terminal has solid documentation here:
https://ia800600.us.archive.org/22/items/CommodoreModem300UsersManual/Commodore_Modem_300_Users_Manual.pdf

things i'd check first:
- is the modem in Originate or Answer mode (via the external switch)?
- are the modems both set to Half/8/N/1?

if you try dialing from the hayes modem (as originator) to the commodore 300, does the ATA recognize the hayes touch tones? if it does, i would suspect an issue with either the commodore 300 or the c64 itself (e.g. capacitor values out of whack due to age, causing the audio frequencies to drift out of range).

Show threadgridbugsFeb 5

@vga256 Question about Half/8/N/1: How does one configure these settings on the Hayes modem? There don't seem to be any AT commands for it. I was starting to think that these were properties of the serial port side of the modem and not the telecom side, and if they're misconfigured then the modems would still handshake but I'd see garbled text when I actually started transmitting data over the connection.

I'm using novaterm 9.6 on the commodore. I've also tried something called "first term" which supports using the SID chip to generate touch tones if you plug the audio out from the commodore 64 into the modem, but my ATA doesn't seem to recognize them. I've had some success playing touch tones generated by an Android app into the "audio in" port of the commodore modem. But the most approach has been to start the call on a real phone and then hand it over to the modem before the other side picks up as described in my original post.

The ATA recognizes the hayes touch tones. I can call my mobile with an ATDT command. I've tried calling the commodore from the hayes, and it rings but there's no indication on the commodore side that anything is happening, _except_ that I can use novaterm's "hang up" command which ends the call.

I actually have the physical copy of the Commodore 300 user manual which includes a large section about Common Sense. I briefly tried it out but it didn't seem to be working properly so I switched to novaterm. Might give it another shot and see if it can generate touch tones that my ATA recognizes.

Show threadRegionales Retro-RechenzentrumFeb 4

@gridbugs Check:

https://osmocom.org/projects/retronetworking/wiki/Software_PBX

https://www.osmocom.org/projects/octoi/wiki

Software PBX - Retronetworking - Open Source Mobile Communications

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