Need help with carier detect?

Sat Jan 19 05:12:29 AEST 1991

I have noticed a problem with our microvax,  it appears not to 
disconnect the process when someone hangs up without loggin off.
I have checked the signals documentation and everything looks to be 
correct.  It drops the DTR line fine when someone logs off,  but
I can't seem to get it to recognize carier detect.  I also must admit
I find it a bit confusing to me as well.
Has anyone else experienced any conditions a long these lines?

My machine is a Microvax running 4.3-bsd I almost forgot to say that.

Please mail any responses to kirk at braille.uwo.ca, I don't follow
these newsgroups regularly.

Thanx
  Kirk