Shared Serial Line on a DS3100?

[Dan Senderowicz]

I was wondering if anybody succeded setting up a serial line for
outgoing and incoming calls on a DecStation3100 running
Ultrix3.1. I first set the /etc/ttys flag "shared", but the
system doesn't seem to be running "getty". It will only do it if
I set the "on" flag on /etc/ttys, in which case I cannot use it
for outgoing calls ("shared line in use").  Any clues will be
greatly appreciated.

Dan.