two-way communication through the same port under SunOs 4.0?

[Peter Shenkin]

According to my SunOs 4.0 manuals, as of this release you're supposed to
be able to run a getty on ttya to enable logins, and simultaneously hook
an outgoing modem onto the same hardware port, calling it /dev/cua0.
Whichever application (login or, eg, tip) grabs the port first is supposed
to lock it to other applications.  I've tried this, and I think I have all
my gettytab, ttytab and /etc/remote entries correct, but the getty on ttya
(or ttyd0, or ttym0, no matter how I try it) renders /dev/cua0 busy for
outgoing calls.  According to my manual, this isn't supposed to happen.

This is on a 386i, but a colleague trying the identical things on a 3-160
running 4.0 exhibits the identical symptoms.

Has anyone gotten it to work, or is it a known bug, or what?
-- 
Peter S. Shenkin, Department of Chemistry, Barnard College, Columbia University
New York, NY   10027  NEW TEL !!: (212) 854-1418 (work);  (212) 829-5363 (home)
shenkin at cubsun.bio.columbia.edu    shenkin%cubsun.bio.columbia.edu at cuvmb.BITNET