Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!uhccux!munnari.oz.au!murtoa.cs.mu.oz.au!ditmela!yarra!chris
From: chris@yarra.oz.au (Chris Jankowski)
Newsgroups: comp.dcom.modems
Subject: What are V22(bis) guard tones used for and when?
Keywords: V22 V22bis guard tone
Message-ID: <4282@yarra.oz.au>
Date: 13 Sep 89 08:13:50 GMT
Organization: Pyramid Technology Australia, Melbourne
Lines: 18

My TrailBlazer manual lists the following options to select guard tones
apparently used by V22 and V22bis modems during call establishment:
	S91=0	- no guard tone
	S91=1	- use 1800 Hz guard tone
	S91=2	- use 550 Hz guard tone
Questions:
	-What are the guard tones for?
	-Why you have three options here and are they mutually exclusive?
	-Is there any indication what modem may use which option - by country
of manufacturing perhaps?

      -m-------   Chris Jankowski - Senior Systems Engineer chris@yarra.oz{.au}
    ---mmm-----   Pyramid  Technology  Australia	    fax  +61 3 820 0536
  -----mmmmm---   11th Floor, 14 Queens Road                tel. +61 3 820 0711
-------mmmmmmm-   Melbourne, Victoria, 3004       AUSTRALIA       (03) 820 0711

"Knowing how things work is the basis for appreciation,
and is thus a source of civilized delight."  -- William Safire