2.6 Direct serial lines

If you have a direct serial line between two unix machines, or a unix machine and something else, and want to run a getty program on the unix side that should not interfere with outgoing traffic (e.g.: two unix machines, both sides running gettys, both sides able to initiate an uucp connection), you can also use mgetty. Start it with the ‘-r’ flag (as with uugetty), and it will not try to initialize the modem or wait for RINGs. It will just sit silently on the port and wait… You won’t see /etc/issue on the other side until mgetty gets at least one character, this prevents two mgettys from talking to each other.

This may be valid for leased lines with modems in leased line mode as well, but that may depend on your modem setup.