[Asterisk-Users] FAX over IAX

[James Sharp]

The way I've seen it done is that the incoming fax signal is digitized and
compressed, then sent over the IP channel.  It is done in real time.  You
end up taking up 7k-14kbps instead of the 32/64kbps you'd use to pass high
enough audio quality to not irritate the modems.

Unfortunately, this takes the same DSP work that is necessary to provide
fax transmission/reception...and there have been problems with making that
work.

>
> I think the real solution is some piggy backed protocol that can be told
>  this is fax information at one end, digitize the fax as if it were a
> faxmodem, stream it to the other end using a non-realtime protocol, and
> then initiate a fax call at the other end and restream out the data, all
>  while possibly holding open the original call to indicate reception
> confirmation at the end.
>
>