[Asterisk-Dev] FAX Subsystem discussion.

[John Harragin]

Chad,

> What I am most interested in is a way to attach a fax to an Asterisk FXS
> port and then connect through IAX (prefered) to another asterisk system
> to connect to a T1 card for transmission to the PSTN.
>
> Fax - FXS - * - WAN - * T1 - PSTN.
>
> While direct conversion of the channel to a bitstream over IAX would be
nice,

> ...a store and forward would do in most cases.

This is what I am proposing. I think it would be easier and much more solid
than attempting to send the fax stream over IP (In your case, it would be
very simple to apply compression to the intermediate file prior to
transmission). If we persued the other route of streaming the fax data
live,there would be issues with handshaking through transmission delay, echo
problems, some fax machines would be more stringent regarding handshake
timings, we would need special echocans, the transmission rate would be
low - in fact this would probably lead to overall slower faxing, higher
telco minutes, the list would go on and on. Because of this, building a
virtual device driver for hylafax would ultimately be a waste of time.
However, utilizing its functional blocks might be great, as it already does
almost all of the things we need...

Additionally, it might be done in a new cvs agtools (asterisk gpled tools)
we could use big parts of a gpled fax program (providing a suitable one
exists) - since it would be a separate app wouldn't this approach not
interfere with the Asterisk licence? Or, if hylafax source lends itself to
queue then transmit - there would be no problem (see below). We also might
talk to the hylafax developers - as they might be interested in maintaining
asterisk call functionality in their source - * would give them a lot too...

John





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