D-Modem/README.jerry.md

D-Modem

Software modem with sound
For burble's retro voip modem https://burble.dn42/retro/modem/
Fortunately this old proprietary software modem still works :)

Prerequisite

• A desktop GNU/Linux distribution, livecd is also OK
• See the original README
• Modem without any sound isn't a real modem? No problem, pulseaudio is used to output modem sound in realtime. You must have pulseaudio dev package installed on your system to compile this software.

Step-by-step instruction

Execute these commands as a normal user:

make
./slmodemd/slmodemd -e ./d-modem
screen /tmp/ttySL0 115200

Inside the serial console, use the following at commands:

>atx3
OK
>at+ms=22,0,1200,1200
OK
>atd424026019@voip.burble.dn42
...

Now you should be connected. See https://burble.dn42/retro/modem/ for login username and password. Once logged in, close out of screen and execute pppd like this:

sudo pppd $(readlink /tmp/ttySL0) 1200 user dn42 noauth nodefaultroute nodetach

nodefaultroute is used here to keep your voip alive :)

netns

If you would like a full dialup dn42 experience, try using netns:

sudo ip netns add modem
sudo ip netns exec modem pppd $(readlink /tmp/ttySL0) 1200 user dn42 noauth nodefaultroute nodetatch

Start a new terminal and

sudo ip netns exec modem $SHELL
unshare -m
echo 172.23.0.53 > /tmp/resolv.conf
mount --bind /tmp/resolv.conf /etc/resolv.conf
ping burble.dn42

Have fun!