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From: rjg@umnstat.uucp (Robert J. Granvin)
Newsgroups: comp.dcom.modems,biz.comp.telebit
Subject: Re: connect problems with T2500
Keywords: Telebit T2500 T1000 TrailBlazer Plus PEP connect problems
Message-ID: <1990Dec19.190528.17737@cs.umn.edu>
Date: 19 Dec 90 19:05:28 GMT
References: <1990Dec19.044634.26743@sopwith>
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Reply-To: rjg@umnstat.stat.umn.edu (Robert J. Granvin)
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I know I'll be corrected where I make misteaks... :-)

In article <1990Dec19.044634.26743@sopwith> snoopy@sopwith.UUCP (Snoopy) writes:
|A local site recently installed a shiny new Telebit T2500.  It
|seems that TrailBlazer Plus modems (4.0 ROMs) cannot connect to
|it in PEP mode.  T1000 modems can.  How bizzare.  A similar T2500
|only 2-3 weeks older, but with different ROMs ( GE6.01-T2500 )
|programmed nearly the same (modulo a few rs232 settings that
|"shouldn't" matter, and a couple new registers that the new ROMs
|have that the old ROMs don't) works fine.
|
|Listening in, both the V.32 and PEP tones sound significantly different
|than other Telebits.
|
|Local Telebit wizards are baffled.  Theories: (1) There is something
|"broken" in this T2500.  (2) The GF7.00 ROMs are bad, Telebit didn't
|do enough regression testing.
|
|Ideas, netland?

The 7.0 ROMs incorporate an extra tone to solve echo suppression problems
on the Sprint network.  Unfortunately, ROMs below 5.0 don't know too much
about that, so they won't sync up.

The T2500 could turn on the undocumented register that puts it back into
"old" tones (I forget the register.  It was posted here recently.)  The
other solution is to call Telebit and ask for the BC5.10A ROMs for the
TB+.  (Don't let them give you a hard time about it... Though I don't
suspect they will... :-)

Be warned, though, if you upgrade the TB+, other TB+'s with less than
5.0 ROMs will see the same problems with your upgraded modem that you
were seeing with the T2500.  (You have the same options to solve the
problem there... Set the undocumented register, or update the other
neighbor modems... Snowball effect.)

Robert J. Granvin                           E/Mail: rjg@umnstat.stat.umn.edu
User Services Specialist                    AT&T:   +1 612 625 9224
School of Statistics
University of Minnesota