Problems with a 9600 baud modem connecting at 2400 baud

Nov 3 19:56 UTC 1991

I recently purchased a GVC 9600 bps V.42bis/MNP5 modem.  When I
call Grex, I first set the modem's speed to 2400 baud, get the
usual "CONNECT 2400" message when Grex's modem answers, but find
that to get the login prompt I have to send a break.  With my
Practical Peripherals 2400, this was never necessary -- I'd
always get the login prompt without having to send anything.

With M-Net the situation is somewhat worse.  When I dial the guest
number at 2400 baud, I often don't even get the "CONNECT 2400"
message, even though M-Net's modem is emitting a carrier tone.
Sending a break at this point disconnects me.

Why the new behavior?  Is it possible to set the GVC so that it
behaves the way my PPI did?

response 2 of 12:

Nov 4 05:16 UTC 1991

Yes, this should solve your problem.  The problem is that, when your
modem has MNP enabled, it sends some "feeler" characters to the other
end, which will inititate an MNP negotiation if the other modem supports
it.  Unfortunately, Grex's modems don't support MNP, and so these
handshaking characters are interpreted by Grex as an attempt to log in,
sometimes with disasterous results.

The best way to avoid this is to always disable MNP when calling systems
which don't support it.  I do this by setting up two different dialing
prefixes in my comm. program, one which turns MNP on, and the other
which turns MNP off.  Then, I just select the proper one when I enter
the phone number of the BBS in my dialing directory.

response 4 of 12:

Nov 4 10:58 UTC 1991

Thanks, at\n0 did the trick.  (Thought I'd tried that in the course
of my experimentation, but must've missed it.)

According to my manual, the command for MNP-or-disconnect is at\n2,
not at\n4.

response 6 of 12:

Nov 4 11:41 UTC 1991

Hmm...  I still don't know what trellis coding is, but have discovered
that turning it off fixes my problem with connecting to M-Net.
(The setting doesn't seem to matter with Grex's modems, though.)

response 8 of 12:

Nov 10 14:38 UTC 1991

Well, it turned out that my problem connecting with M-Net wasn't
fixed after all.  On most of the lines (apparently the ones with the
Courier and PC-Club modems on them), the GVC would almost always fail
to connect at all, regardless of how I configured it.  Once in a
great while I'd get a successful connection, but that occurred very
rarely.

I returned the GVC and replaced it with a Practical Peripherals
9600SA.  The problem disappeared; I now have no difficulty connecting
to M-Net.

I'd recommend avoiding the GVC modem.

response 10 of 12:

Sep 1 02:00 UTC 1992

AARGH!  I should have read this item before messing around with my
new modem.  It would have saved me a lot of hassle.  I eventually
figured it out by simply experimenting with changing modem parameters.

response 12 of 12:

Feb 14 00:10 UTC 1993

yup, \N0 means NO!