[Asterisk-Users] faxing

[Darren Nickerson]

> What are your experiences with faxing through Asterisk to the PSTN?
>
> We are using g.711u as a codec, and are originating/terminating with
Broadvox as
> well as through our own PSTN gateways.
>
> We have had some luck with incoming faxes coming into our network from
Broadvox
> DIDs.  They work 50% of the time.  Not sure yet on PSTN incoming since
nobody
> that is using FAX is in our local rate centers.
>
> Outgoing has been bad.  It seems to work the best if the Sipura user
agents have
> echo cancelation off, but we have to have echo cancelation on our outbound
> gateways or there is echo in the voice path.  Faxing outbound works very
> rarely, and if it does, it usually can only send a page or two before we
get
> the infamous "Poor line condition".
>
> Does anyone have a suitable FAX setup working?

Our company's ourbound faxing (as well as the tpc.int fax server I run
personally) goes through Asterisk with no problems to speak of. I recall the
gain settings in Asterisk and on our Adit 600 channel bank needed some
tuning, but it seems to work well now. The negotiated V.34 fax speeds are
slightly lower than a direct PSTN hookup, but we're rarely in that much of a
hurry ;-)

As far as I know, echo cancelation routines/devices are meant to detect fax
tones and shut themselves off. I saw this in action once ... while playing a
recorded fax call back to a customer Asterisk turned off echo cancelation
and my call was instantly very ... entertaining (for me at least - the call
still sounded normal for the customer).

As for using lines from Broadvox, even with g.711u codec, I would think all
bets are off. The only reliable option for fax over VoIP is probably going
to be t.38 (when it grows up).

-Darren

--
Darren Nickerson
Senior Sales & Support Engineer
iFax Solutions, Inc. www.ifax.com
darren.nickerson at ifax.com
+1.215.438.4638 x8106
+1.215.243.8335 (fax)