[nSLUG] Problem with efax & USR Faxmodem

Dop Ganger nslug at fop.ns.ca
Thu Nov 29 09:14:53 AST 2012

On Wed, 28 Nov 2012, Mike Spencer wrote:

> dop> My first guess would be to try using class 2.0 if you're using
> dop> class 1 faxing, or if you are using class 2.0 use class 1.
> The efax docs refer to classes 2.0, 2, and 1.  I tried 2.0 (default)
> and  altering the script to use 2.  Didn't try 1.

Don't use Class 2 with USR modems, that's for Rockwell. You may find Class 
1 works better as that offloads more of the protocol side to the PC and 
treats the modem as more of a data transport than letting it do any great 
amount of error correction and the like.

>> Also make sure the bit rate on the serial port is set high enough
>> that it won't choke sending data through; 38400 or 57600 should do
>> the trick, or 115200 if your hardware can take it (ie, 16550 UARTs).
> The script I use for dialup explicitly tells pppd to set the UART to
> 115200.  I'm not certain if the setting gets reverted to some other
> default when pppd exits nor if efax explicitly sets that. A quick
> browse of the efax script and docs finds no mention of this item.

If efax changes the bit rate on the serial port during modem 
initialisation the modem will autobaud to the correct speed. It might be 
worth double checking; if efax is trying to run at 19200 and the fax 
connection is 14400 the data could be coming through fast enough after 
compression to choke the serial port and cause the failure.

That said, almost all fax software I've ever used has been flakey to some 
degree, no matter what flavour modem is used (compatibility testing was a 
particular bane of mine). I can only recall one piece of software that 
ever worked reliably and gave sane explanations when it failed, and that 
was a piece of DOS software called BGFax. Casting around on the net it 
seems like it's still available at http://www.bgfax.com/bgfax.htm if you 
have a DOS machine kicking around (or want to try it under Dosbox or 

Cheers... Dop.

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