Section 8 : General Telecommunications & Modems

Q803: How can I tell if my modem supports 2D compression?

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Q.
How can I tell if my modem supports 2D compression?

A.
From: Dmitry Bely <dbely@mail.ru>
Subject: Re: flexfax: Q about elsa modem
Date: 16 March 2000 17:44
> i use an elsa microlink 56k basic with hylafax and the config file
> from their webpage. everything runs good but i only get 1D connections.
>
> the config files uses Class2.0.
> i have no use2d: no anywhere
> no corrupt info files
>
> i called elsa support and they do not know wether their product
> supports 2D encoding or not!?!!

You can easily get this info yourself. Issue in any terminal program (e.g. minicom) the following commands: 

AT+FCLASS=2.0;+FCC=?
You will get something like 
(0,1),(0-5),(0-2),(0-2),(0,1),(0,1),(0),(0-7)
OK
(That's what my Zyxel 1496e responded).

The parameters above are
VR,BR,WD,LN,DF,EC,BF,ST

The fifth parameter (DF) is the range of DCE-supported data compression methods according to the following table:
DFData Compression Format 0 1-D Modified Huffman (T.4)
*1 2-D Modified Read (T.4)
*2 2-D Uncompressed Mode (T.4)
*3 2-D Modified Modified Read (T.6)

So if your modem returns just (0), 1-D is the only compression format supported.
BTW, this command id valid for Class 2.0 only.

Hope to hear from you soon,
Dmitry

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