RetroNetCall: "ISDN B-Channel protocols"
I've presented about ISDN B-Channel protocols (X.75, V.120, V.110, T.70, ...) as part of the RetroNetCall talk series on retro-networking technology.
You can find the video recording at https://media.ccc.de/v/retronetcall-20221207-laforge-isdn-b-channel-protocols
Many people with some kind of telecom background are familiar with D-channel (signalling) protocols of ISDN, and you can find many publications on that topic. Surprisingly, much less publications are talking about the B-channel protocols used for data transmission, like VX.75, V.110, V.120, T.70, ...