[comp.dcom.modems] What are V22

chris@yarra.oz.au (Chris Jankowski) (09/13/89)

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?

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