Kids these days ;) . Before ssh there was telnet, and a telnet server can write a greeting text before asking for your username (it can even be configured to skip the login and just show you a shell), e.g.: https://www.youtube.com/watch?v=tno79Q2X-Sg&t=31
In that video it says "User Access Verification", he probably changed his to "Dept. of Defense"...
Before we had that, we had modems, which I assume was the case since wardialing is mentioned. They could run ANY protocol - or indeed none at all. You could tie it directly to the text I/O of any program(easy on unix systems, not as easy on MSDOS or early Windows versions). Many "BBS" systems worked this way.
EDIT: also early "multiplayer" games, which would talk to the modem directly. I've spend hours playing Descent over a 9600bps modem connection. That was only running... whatever protocol Descent used. You kids and your fancy packets.
If a file was being transferred you could do nothing else. If you were specially high-tech, you would use ZModem for the transfer. If not, you would be using something like XModem, or even Kermit or something proprietary.
In that video it says "User Access Verification", he probably changed his to "Dept. of Defense"...