Hayes modem on a sun4

[Rich Winkel UMC Math Department]

I have a hayes compatible modem on a sun 4, hooked to an office telephone
line.  I'd like to have cron set the modem up for auto-answer at night and
turn it off during the day.  My (almost working) kludge is to have
two versions of ttytab, one with the appropriate port set on, the other
with it set off.  By renaming the appropriate file to ttytab and
doing a 'kill -HUP 1', I can (almost) get the DTR line to toggle on and
off (the modem won't answer when DTR is off).  That is, if DTR is off,
I can turn it on by putting a getty on the port via the above method.
BUT, once DTR is on, simply setting the port off in ttytab doesn't make
DTR drop.  If tip is run on the port, then DTR drops when tip exits.
Does anyone have any ideas?

By the way, thanks to all my respondents for helping with my syslogd problem!
Another case of NRTFM!

Rich