[Asterisk-Users] Which is the best fax-modem for testing ?

[Rich Adamson]

> Which fax-modem would you pick if you had to test fax capabilities ?
>  
> For instance, before releasing a new PBX system offering fax 
> connectivity, you would like to make sure you "comply" with most fax 
> machines and protocols.
> As you can't afford you buy and maintain tens of such fax machines nor 
> can't afford to test by hand each protocol, it's tempting to buy an 
> all-inclusive fax-modem and run a program instead.
> Which one would you choose for that ?

The fax modem is not really the issue with asterisk. By far, the 
majority of existing analog fax machines installed and being sold today 
will function just fine with asterisk.

If you sell an asterisk system into an analog pstn environment, any fax 
machine will function through asterisk "if" you use the Sangoma A200D 
analog card with fxo and fxs modules. (Very stable and very reliable fax 
transmissions.)

If you sell an asterisk system into a digital pstn environment (eg, 
PRI), any fax machine will work with Sangoma or Digium digital cards, 
however the fxs interface to the fax machine "may be" very questionable 
in terms of reliability and usability.

If you sell an asterisk system with external pstn gateways (eg, ATA 
adapters), better be careful as the majority of inexpensive gateways 
will not function reliably with an analog fax machine.

If you're thinking T.38 fax capability, forget it for now. Some folks 
were working on adding T.38 support into asterisk, but its not in stable 
code as yet to the best of my knowledge.  Also, according to Steve 
Underwood, T.38 implementations in current fax machines are of 
questionable quality.

If you're thinking in terms of high volume faxing, then look towards the 
hylafax (or whatever) approach.

If you're thinking in terms of faxing via VoIP providers, reliability 
will be less then acceptable "if" you get it to work at all.

Bottom line: the most reliable method of integrating fax support into an 
asterisk system "today" (without implementing hylafax or whatever) is 
through the use of the Sangoma A200D analog card, as it keeps the pcm 
data flow "on the card" (fxs -> fxo); and, removes the impact that pci 
bus, shared interrupts, system applications, ethernet dropped packets or 
jitter, ATA issues, and other disruptive elements from the analog fax 
data path.

If you search the list archives for the past two years, you'll find a 
couple of "point" solutions other then mentioned above that do work, but 
most of them are "dependent" on some specific element (eg, full moon) 
that cannot be reliably replicated in every asterisk installation.