[Asterisk-Users] Which asterisk-friendly cards are fax-capable?

[Lee Howard]

Tom Rymes wrote:

> On Oct 12, 2005, at 11:26 AM, Lee Howard wrote:
>
>> Tom Rymes wrote:
>>
>>
>>> (I would like to be able to receive faxes reliably
>>> over our PRI)
>>>
>>> Until then, however, I still recommend HylaFAX.
>>
>>
>> If your PRI comes in to a TE405P or somesuch then you can pass fax  
>> DIDs out through another port on the TE405P and out to a T1  faxmodem 
>> (such as a Patton 2977) or a T1 channel bank and then to  analog modems.
>
>
> Good call, Lee. Unfortunately, we only have a single port Sangoma  
> card in our asterisk server. In order to do what you suggest, I would  
> have to buy a dual port card and a channel bank or T1 modem. Thats  
> more $$$ than is warranted by our fax traffic.


IAXmodem then ;-)  As long as you're okay with V.29 (9600 bps).  Keep a 
back-up analog line around attached to a hardware modem until you're 
completely certain that IAXmodem is working perfectly for your needs.

> Also, given reports of problems related to frame-slippage and other  
> weirdness encountered when sending data/fax through Asterisk, I'm  
> reluctant to invest that money. Have you tried this setup yourself? 


Yes I have a Patton 2977 (driven by HylaFAX), connected via crossover to 
one port on a TE405P (driven by Asterisk) which has another port 
connected to the T1 from the telco.  Asterisk bridges the two for 
sending and receiving.  Receiving is wonderful.  Sending is also quite 
good, however, there are some quirks with the Patton firmware which need 
to be resolved for me to be completely delighted.

I've faxed with IAXmodem through that same TE405P without any troubles.  
I've also faxed with IAXmodem through an X100P without troubles.  I've 
never used any of the TDM cards from Digium.  Lots of people seem to 
report other kinds of fax failures with them, and I don't know more than 
that to comment on it.  People have talked about frame slips a lot, and 
I'm not really sure what to make of it.  My understanding is that a 
frame slip causes a momentary audio disruption (as far as the audio 
stream goes).  So I would think that as long as it's not happening at 
inopportune moments or in a frequent manner that a single frame slip 
shouldn't really take down a fax session.  But, I'm sure that it would 
depend on the software.  As far as HylaFAX goes, it wouldn't notice the 
frame slip.  The modem would, and it would probably report it as corrupt 
data or carrier loss... from which both are easily recoverable.

Lee.