[asterisk-dev] Bug in SendFax/ReceiveFax ?

[David Backeberg]

2009/9/14 Håkon Nessjøen <haakon at avelia.no>:
> Hi,
>
> It seems like asterisk does not like to send faxes to itself:
>
> The cal is set up using a call file with Local/exten at context and
> Application: SendFax()
>
> [Sep 14 14:53:53] WARNING[8817]: app_fax.c:439 transmit_audio: It looks like
> we hung. Aborting.
> [Sep 14 14:53:53] WARNING[8817]: app_fax.c:173 phase_e_handler: Error
> transmitting fax. result=49: The call dropped prematurely.
> [Sep 14 14:53:53] WARNING[8817]: app_fax.c:618 transmit: Transmission error
> [Sep 14 14:53:53] WARNING[8818]: app_fax.c:173 phase_e_handler: Error
> transmitting fax. result=49: The call dropped prematurely.
> [Sep 14 14:53:53] WARNING[8818]: app_fax.c:618 transmit: Transmission error
>
> Fax sending/transmitting is working great going in or out via DAHDI, but
> when i send a fax to a fax receiver at the same asterisk machine, it hangs,
> and then gives up after some while, with the werror message shown.
>
> Can easily be reproduced by SendFax()ing to a ReceiveFax() on the same
> server. (Tested on *1.6.0.5 with spandsp0.0.5, could someone test this on
> trunk?)

I've previously set up a similar test, but used thousands of call
files to 'burn-in' T.38 faxing between two asterisk systems. The faxes
completed reliably thousands of times.

I never tried your arrangement with a LOCAL channel. There may be
something interesting about LOCAL channel faxing that shouldn't be
done. Perhaps faxing on loopback-style local channels is broken? If
you do put it into the bugtracker, be sure to point out that it's
LOCAL channel faxing that's not working for you.

For a workaround, you should either setup a loopback T1 cable with
your card, or set up two systems to bounce calls at each other.