Path: utzoo!attcan!uunet!steinmetz!davidsen
From: davidsen@steinmetz.ge.com (William E. Davidsen Jr)
Newsgroups: comp.dcom.modems
Subject: Re: help - Courier HST doesn't connect to us at 1200 bps
Keywords: MNP checking
Message-ID: <12845@steinmetz.ge.com>
Date: 20 Dec 88 19:31:47 GMT
References: <1988Dec11.125951.10539@lsuc.uucp> <13271@ncoast.UUCP>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Organization: General Electric CRD, Schenectady, NY
Lines: 31

In article <13271@ncoast.UUCP> mikes@ncoast.UUCP (Mike Squires) writes:

| I have had similar problems with my HST that were eliminated by asking the
| HST to not check for MNP (AT &M0).  I had problems with both an ARK 24K
| and AT&T modem of this type.


  This can be a problem with any MNP modem, particularly calling into a
system which has good response. The problem only happens when the
calling modem has MNP and the answering modem doesn't.

  What happens is that the modems exchange tones and whistles until they
find a mutually satisfactory protocol and connect. The carrier detect
goes true. At this point if the called system does login and/or
autobaud, there may be a problem. The calling modem sends out a
particular tone bust which means "would you like to do MNP?" If the
called modem is not MNP, this burst gets passed on to the autobaud
program, which may set speed to 134.5 or something. Then then end of the
tone burst may get passed into the login sequence.

  Now the two systems are talking at a bad baudrate, neither able to
understand the other. Needless to say, if the autobaud has already
decided that the speed is set, nothing short of a start-over will make
the connection work.

  Hope this clarifies the sequence.

-- 
	bill davidsen		(wedu@ge-crd.arpa)
  {uunet | philabs}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -me