Dial-in serial getty

[Steve Keller <keller.steve@gmx.de>]

For some retro feeling I grabbed my old modem and attached it to the
phone line. Minicom and dial-out work but now I'd like to allow
dial-in with a getty waiting on the line.

Systemd has a serial-getty@ service which uses agetty but that doesn't
work. It seems agetty is just not suited for that job although the
manual page claims it to be.  But I couldn't get agetty to wait for an
incoming call, answer it, and then send the login prompt. Instead, it
always immediately sends the prompt, execve()s to /bin/login which then
terminates after a 60s timeout.

I've now installed mgetty but there is no systemd service file for it.

Should I change the serial-getty@ service to use mgetty or should I
create a new service for it?  In case of the latter, does it suffice
to only add the .service file or do I need anything else?

Steve