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From: bartm@cv.ruu.nl (Bart Muyzer)
Newsgroups: comp.sys.hp,comp.dcom.modems
Subject: HP37212B modem refuses to answer phone!!!
Summary: silence, rude, no answer
Keywords: no answer on incoming calls
Message-ID: <1991Apr25.154031.2013@cv.ruu.nl>
Date: 25 Apr 91 15:40:31 GMT
Sender: usenet@cv.ruu.nl (placeholder for future)
Organization: University of Utrecht, 3D Computer Vision Research Group
Lines: 57
Nntp-Posting-Host: mind

Hi,

I'm experiencing a problem with a HP37212B "Error Correcting Modem". I know
what causes it but I don't know what to do about it (except rebooting :-( ).
The modem is connected to a HP 9000/835 using a mux which (among others) also
attaches the system console to the system. This one works fine so I know it's
not the mux.

The problem is that the modem refuses to pick up the phone because the MDTR
is low. So it thinks the connected computer isn't ready and refuses to
answer. This situation occurs after the following sequence:
* user calls and logs in
* user initiates to be called back
* user hangs up and gets called back
* user works and hangs up
Now the modem never answers any further incoming calls. The RI(ng) light is on
during a ring but no answer...

The callback service uses the 'ct' program supplied by HP. As long as this
service isn't used, things seem to keep working fine. Even if I call the
modem, wait for it to start whistling and then throw down the hook things keep
working.

I used the following tricks to make the modem listen again:
* for a while, it worked to have the modem initiate a call using 'cu'. This
  somehow reset the modem and it all worked again;
* it sometimes helped to kill a process called 'uugetty'. Init restarts it and
  all is fine again;
* If this fails, the only thing left is to reset the 835. 

A HP technician looked at the modem and even replaced the entire printboard,
but this didn't help. And I think (from the above) the modem is not to blame 
but the 835 because it messes around with the MDTR signal.

Questions:
1. Can anybody provide an "off shelve" solution?
2. Is it possible that 'ct' doesn't properly reset things on exit?
3. Is there some way to flip the MDTR signal to "active" without rebooting?
4. Did I miss some modem configuration stuff (yes, I tried setting MDTR 
   always high using dipswithes on the modem, but this doesn't work either
   since the modem picks up the phone but I never get a login prompt)
5. Are there any PD 'callback programs" available. If yes, where can they be
   ftp'd from?

Any help will be appreciated.

						>] Bart [<
--
Bart Muyzer(SysAdm), 3D Computer Vision, University Hospital Utrecht
Heidelberglaan 100, Room E 02.222, 3584 CX Utrecht, The Netherlands.
tel: +31-30-506711 (w), +31-3402-52157 (h)  | "You never get a second chance
fax: +31-30-513399, e-mail: bartm@cv.ruu.nl |  to make a first impression"