Getting a USR 5637 USB modem working with v.23 1200 / 75 reddit / bbs ---------------------------------------------------------------------- marrold-the-second · 2022-01-31 21:14 Bit of a long shot but if anyone knows they're probably here. I'm trying to get a USR 5637 modem working with v.23 1200/75 to connect to a [Viewdata service](https://glasstty.com/?p=1) Unfortunatly it's a unreliable when getting a connection. Sometimes it works after a long time, other times it fails. When it fails I don't hear the low tone associated with the back channel. When I use a USR Courier the connection is almost instant, and works every time. There are some settings relating to the modulation and speed limits etc but none seem to improve the reliability. Has anyone got any suggestions? ---------------------------------------------------------------------- PhotoJim99 · 2022-02-01 15:52 I don't have an answer to your specific problem, but I've been tinkering with modem connections between two cablemodem-based "POTS" (really VoIP over cablemodem) phone lines lately, including with a USR5637. On the one end I have a Courier v.Everything v.90 (USR5607). When I dial with a PCMCIA Courier v.Everything in v.34 mode, I get connections in the 28800-31200 bps range. (In HST mode it connects consistently at maximum 16800 HST speed.) When I dial in with a PCMCIA USR modem (3CXM556), I get connections in the 26400-33600 range. When I dial in with the USR5637, more often than not I connect in v.32ter mode at 19200 bps. Occasionally I will get in the low 20k bps range in v.34 mode. As much as I like the USR5637 as a USB hardware modem in a world where few such modems exist... it really seems to be a terrible modem in a lot of ways. I have several of them and perhaps I should experiment. It's possible the hardware has changed over the years. ---------------------------------------------------------------------- marrold-the-second · 2022-02-01 15:55 Hey thanks for the info, its definitely plausible the 5637s just arent as good as the old stuff. I tweaked some more stuff and thought I'd fixed it ( I was using the wrong codec so it was being transcoded somewhere which is bad news ) but it's still hit and miss. As it's still being made / sold I've raised a support ticket with USR but I'm not very hopeful. ---------------------------------------------------------------------- PhotoJim99 · 2022-02-01 16:07 Do you have another 5637? It would be interesting to see what happen if you connect two together at v.23 speeds. I can tinker in a few days if it's helpful and you give me the AT commands you used (and I can check my command reference to see if anything seems awry). ---------------------------------------------------------------------- marrold-the-second · 2022-02-01 16:10 I do have two actually, good thinking. It'll take me a few days to get something setup to test them though and I've not actually done anything with *answering* a call. Any suggestions on something I can quickly throw up on Linux / Raspberry Pi OS just to test it? ---------------------------------------------------------------------- PhotoJim99 · 2022-02-01 16:22 Dial-up console! If you use systemd, just install the 'mgetty' package and put this in /etc/systemd/system : /etc/systemd/system/mgetty.service [Unit] Description=Modem Getty (mgetty) Documentation=man:mgetty(8) Requires=systemd-udev-settle.service After=systemd-udev-settle.service [Service] Type=simple ExecStart=/sbin/mgetty -n2 -x5 -s 230400 /dev/serial/by- id/usb-1a86_USB2.0-Ser_-if00-port0 Restart=always PIDfile=/var/run/mgetty.pid.usb-1a86_USB2.0-Ser_-if00-port0 [Install] WantedBy=multi-user.target Re: the 'ExecStart' line, -n2 answers after two rings (change to one if you don't use Call Display or don't care, and prefer a faster answer), -x5 is the verbosity level (I could probably turn this down now since it's working fine), -s 230400 is the port rate (use the fastest rate your port supports that is sensible; 460800 will work with the 5637s, but with a lot of USB-to-serial adapters, while they appear to work at 230400 or 460800, they are actually slower than they are at 115200 - this can be established by trying various screen or minicom sessions to the modem and typing in atix (where x is various numbers) looking for a chatty command output, and seeing how quickly it appears on the screen). Once the file is installed: # systemctl daemon-reload # reloads service files # systemctl enable mgetty # enables the service on reboot # systemctl start mgetty # and starts it now as well You should now be able to dial in and log into a shell. Note that the terminal type will be set to 'dumb' by default, which will prevent full-screen stuff from working. If you use bash, you can change the terminal type manually via: $ export TERM=screen (or vt102, or whatever terminal type you need - GNU screen supports 'screen' and makes a nice little terminal program that feels just like a Linux terminal shell except that it's slow :) ). One other thing - I've used the detailed and fixed /dev entry for my modem instead of /dev/ttyACM0 which can change if you have more than one modem, so change accordingly to what you need. ---------------------------------------------------------------------- marrold-the-second · 2022-02-01 16:26 Oh wow thanks, that should cut down the time to test it considerably now I don't have to do the leg work. I'll let you know how I get on. ---------------------------------------------------------------------- PhotoJim99 · 2022-02-01 16:27 Please do!