Path: utzoo!utgpu!watmath!att!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!virtech!dennis
From: dennis@virtech.UUCP (Dennis P. Bednar)
Newsgroups: comp.dcom.modems
Subject: Telebit T2500 to Microcom QX/V32.C problem after upgrade to Rev 1.5
Message-ID: <1018@virtech.UUCP>
Date: 15 Aug 89 20:24:26 GMT
Organization: Virtual Technologies Inc
Lines: 49


The following is a short story about a recent problem we
have found when trying to connect a Telebit T2500 modem
to a Microcom QX/V.32C modem.  We recently upgraded the
EPROM chips in the Microcom modem from Rev 1.1 to Rev 1.5,
and after doing so, the competing vendor modems were no
longer able to connect.  Because it worked with Rev 1.1
but not Rev 1.5, I am inclined to believe that it is not
a configuration problem for either modem.  The message
below was mailed to local users on our machine:

---

There is no errata sheet that describes the enhancements to
rev 1.5 firmware for the microcom QX/V.32.C modems.

I have installed the new chips in only two of the microcom QX/V32.C
modems because there is a problem connecting the Telebit T2500 modem
to the Microcom QX/V32 modem.  The problem is that they connect initially,
then the phone call is immediately disconnected. I called Microcom
Technical Support, and told them the problem occured after upgrading
the Micocom EPROMS from Rev 1.1 to Rev 1.5.  I hesitate to install
the new chips into the third modem because there may be a Rev 1.5.1
to come to fix our problem (lets hope!).

When I found this problem after installing the chips into the
first microcom modem, I did a well-controlled test with the 2nd
microcom QX/V32.C modem still containing the old Rev 1.1 chips:

	I verified that with rev 1.1 of microcom EPROMS, I was
	able to dial in BOTH directions (out of the telebit T2500
	into the Microcom QX/V.32, and vice versa).  I did this with
	a cu(1) running on both modems.

	I then installed the Rev 1.5 chips into the 2nd Microcom
	modem, and repeated the same test.
	In both tests, each modem connected, then dropped the
	phone call within a fraction of a second later.  In a
	few rare cases, a few characters typed into the Microcom 
	modem were transmitted successfully to the terminal at the
	Telebit T2500 end.

I spoke to "Nat" at Microcom about this problem.  Nat also verified
that his Microcom could not communicate with our Telebit modem (by
calling our Telebit from his Microcom modem).  The results were the
same as what I saw when I did the above tests.  His engineers
will check into the problem and he will call us back.

-dennis