[Asterisk-Users] Asterisk mangling faxes

[Steve Underwood]

Hi,

Lee Howard wrote:

> Almost all fax software, including your WinFax 7.0, that supports Fax 
> Class 2, Class 2.0, or Class 2.1 will usually therefore support ECM 
> when the modem (DCE) itself supports ECM in those Fax Classes.  This 
> is because the DCE does the ECM protocol work, and the software (DTE) 
> doesn't really notice the difference.  Using Class 2 for faxing you 
> are mostly subject to the mercy of the modem manufacturer for quality, 
> so any bugs must usually be fixed in firmware.
>
> Modems that I know of that support ECM in some fashion in Class 
> 2/2.0/2.1 are the MultiTech 5634 V92 family (MT5634ZBA-V92, ISI5634, 
> etc.), the Digi AccelePort RAS, and the Eicon Diva Server.  There 
> probably are a few more, but yes, this is a very short list.  Most 
> modems do not support ECM in their Class 2 firmwares.
>
> However, many (although not all, dare I say most?) modems support Fax 
> Class 1 or Class 1.0.  In this mode the faxing is heavily dependent 
> upon the DTE and thus the support or lack of support for ECM comes 
> from the fax software.  Your average fax software that comes on a CD 
> bundled with your modem is not going to support ECM.  Symantec (your 
> WinFax people) recently purchased the rights to Procomm Plus (yes, if 
> you're an old BBSer you may have this on your shelf), which does 
> support ECM in Class 1, so maybe Symantec will get that ECM technology 
> into WinFax eventually.  In the open-source world, HylaFAX now 
> supports ECM in its Class 1 implementation in its current CVS HEAD (to 
> someday become 4.2.0).
>
> I don't know of many other Class 1 Fax Softwares that support ECM.

Are you sure that approach is free from patent problems? I thought the 
ECM protocol was encumbered. If not, that is good news. :-)

Regards,
Steve