[asterisk-users] ReceiveFax

[Larry Moore]

On 19/12/2012 5:46 AM, Andrew Nowrot wrote:
> Hi
>
> I am trying to get faxes to work with Asterisk and ReceiveFax. The
> problem is that I am getting only about 60% of success (for example two
> of six fax transmissions always fails). The most common errors are
> "Error : Unexpected DCN after requested retransmission" and "Error :
> Disconnected after permitted retries".
>
> The scenario is like this:
>
> Fax machine ----- ATA ------ (SIP) ------ Asterisk 11.1.0 ----- ReceiveFax
>
> I am using Cisco SPA122 and Sipura SPA2102 (both with the newest
> firmware). Both are configured to use T38. I can see that Asterisk and
> ATAs negotiate fax T38.
> Is this a common issue with these ATAs. I am obviously doing something
> wrong. Can anyone point me in to right direction. I can provide the logs
> form both good and failing transmission.
> BTW
> Fax machine to fax machine transmission with these ATAs almost always works.
>
> Cheers
>

Just a suggestion, check the current T.38 redundancy value in the SPA's, 
if it isn't set to 3 then set it to 3.

If Asterisk 11 is still using udptl.conf then check the following;

udptlfecentries = 3
udptlfecspan = 3

You may also want to set;

use_even_ports = yes

Good luck.

Larry.