Faxing and PCI (was Re: [Asterisk-Users] Digium cards,

[Doug Lytle]

Olivier Krief wrote:
> 2006/4/18, Doug Lytle <Support at drdos.info <mailto:Support at drdos.info>>:
> Thank you very much for the explaination.
>
> 1. Does using iaxmodem imply that, for example, incoming fax calls are 
> processed that way ?
> - PSTN calls are terminated on TDM board (Digium, Sangoma, ...)
> - the media flow (G711 as it comes from PSTN) is forwarded without any 
> modification to the right instance of iaxmodem software process
I'm using SLIN, but ulaw/alaw would be acceptable.


> - iaxmodem process are "managed" by hylafax application but are seen 
> and identified by Asterisk as IAX softphones (during above mentioned 
> registration)
> - media is processed once, according hylafax config (that often means 
> forwarded to printer or email), after a single "move" from TDM board 
> to server processor through PCI bus
>
On incoming, I'm using a macro to handle all 23 lines.

exten => _50XX,1,Macro(faxreceive,${EXTEN}, ${CALLERIDNUM})

[macro-faxreceive]

exten => s,1,Dial(IAX2/iaxmodem.com01/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com02/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com03/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com04/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com05/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com06/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com07/${ARG1})
exten => s,n,Dial(IAX2/iaxmodem.com08/${ARG1})

If the first modem is busy, jump to the next.  If all are busy, then 
play a busy signal and hang up.

> 2. If it's correct, fax speeds and protocols (V29, G3, ...) are 
> defined by hylafax and iaxmodem

Yes.  The iaxmodem configuration files specify the protocols and speeds 
allowed.  I have mine fixed at 9600.  I'm not sure about G3 though. 
> .
> So, how do hylafax-iaxmodem speeds and protocols compare with those 
> from a standard fax machine ?
> I mean, if you had bought a new fax machine and had it connected to 
> the PSTN, would you get a different set of speeds and protocols ?

Don't know, never tested.  I don't have experience with our current fax 
hardware.
>
> 3. How do iaxmodem and rxfax-txfax DSP functions compare ? Are they 
> using the same library ? Is there any standard allowing iaxmodem or 
> rxfax-txfax to benefit from hardware DSP inside TDM board ?

As far as I know, iaxmodem uses SpanDSP, so they should be identical.  
Lee would be the one to answer technical questions.
>
> 4. How would that scale ? Up to 30 Calls ? Are incoming or outgoing 
> faxes more demanding ? Any hardware recommended ?
>
I've been focusing on incoming, but this weekend I will be setting up a 
few more work stations to help on the outgoing testing.

Doug

-- Ben Franklin quote: "Those who would give up Essential Liberty to 
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