Connecting to analog modem

Hardware Librem 5
1

My last phone, before the enshittocene of mobile phones beginning in the 2010s, was a Nokia E65. It was very simple to use with my computer. Via Infrared or Bluetooth, I could dial 99**1# and use my data connection. Or I could launch Joikuspot and share my data connection via Wi-Fi.

Interestingly, though, I could do standard data connections to analog modems. For example, I could easily dial a local ISP’s number and connect.

I run my own servers at home, with email, nextcloud, etc, all on FreeBSD, and I got a U.S. Robotics Courier modem for out-of-band management. My management box has its console redirected to the serial port and everything works fine. I was wondering if I could somehow dial from the Librem 5, either directly (would be fine for simple management tasks and status checks) or by “exposing the modem” like I used to do with my old Nokia.

Any ideas?

Thanks, as always.

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Interesting, nostalgic and very nerdy :slight_smile: So, you want to call to a number where your modem is waiting and your question is, can L5 make an audio analog data connection to it? (for a moment there I was confused and though you wanted to connect the modem to L5 to act as a modem for it - from possibly flakey 4G to more robust 56.6 :joy: ) Have you done anything like this on linux before?

I think what you need is something like GitHub - kamalmostafa/minimodem: general-purpose software audio FSK modem (search linux audio modem for something that you can install or build to L5) and use that from command line and probably need to call manually with AT commands from command prompt to get L5 audio softmodem to a phone connection (that can maybe be set up as a script under a gui icon). This is just a guess.

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I do not know why this should not work with the L5 modem. Many years ago I owned cellphones, like the Siemens S10, or some Bosch 908 device. They have had V.24. interface, you connected your computer/laptop to it, used kermit to dial ATD1234567 and when it got CONNECT 9600 (9600 baud) you could either talk to the other site offering login: or both ends launched PPP daemons. This was over GSM as carrier, but the called site was a POTS number, i.e. analog. GSM hanled this transparently to your end to V.24. Why should this not work over LTE?

Just run a test, install kermit and dial:

   mmcli -h
   mmcli -L    (gives the modem number)
   mmcli --modem=3
   mmcli --modem=any    (as we have only one modem)

   how to make an shortcut icon for a small terminal app, see:
   https://forums.puri.sm/t/shortcut-to-modem-info/16886

   cat ~/.kermrc
   set escap 21
   set line /dev/ttyUSB3
   set carrier-watch off

   $ sudo kermit ~purism/.kermrc
   C-Kermit 9.0.305 OPEN SOURCE: Alpha.02, 19 Sep 2020, for Linux+SSL+KRB5 (64-bit)
    Copyright (C) 1985, 2020,
     Escape character: Ctrl-U (ASCII 21, NAK): enabled
   Type the escape character followed by C to get back,
   or followed by ? to see other options.
   (/home/purism/) C-Kermit> connect
   atd 1234567890
...

and see what will happen… I could do the test as well, but don’t have any number to dial which is a analog modem.

PS: The Bosch 908 was in March 1999 as I could check in my mails. The Bosch company in Germany lent me the device for such tests.

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Thanks for the suggestions. I am glad to see that there’s potential.

I just found out that, while I still retain DSL, I actually (to save some 5 EUR per month) asked the carrier to disable the phone number connected to the landline.

I will ask to get it reactivated and one it is up, I will try it.

My relatives all have landlines and, whenever I travel to visit them, I carry along a HP Jornada 720 that has a 56kbps modem. It is the perfect machine for a quick remote console visit in case of need. But it would be perfect if it would work from my Librem 5, giving me out-of-band access anywhere in the world.

edit: I plan to connect the modem to one of my main server’s serial port with console redirection set in BIOS, or perhaps just set tty. The modem handles authentication fine, can even have multiple users. This should be enough for my needs.

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