[Freeswitch-users] {Solved} Anyone using t38modem with FS and Hylafax.

[Alex Crow]

On 11/11/11 12:52, Alex Crow wrote:
> If anyone's interested, I've get outbound fax semi-working with this setup:
>
> <extension name="faxoutviamitel" continue="true">
> <condition field="destination_number" expression="^9(\d{4})$">
> <action application="set" data="absolute_codec_string=PCMA"/>
> <action application="set" data="fax_enable_t38=true"/>
> <action application="set" data="sip_execute_on_image=t38_gateway self
> nocng"/>
> <action application="bridge" data="sofia/external/$1 at 10.10.0.2"/>
> </condition>
> </extension>
>
> t38modem is started like this:
>
> t38modem -ttt -o /var/log/t38modem.log --no-h323 -u t38modem
> --sip-register t38modem at 192.168.20.245,secret --sip-listen udp\$*:6060
> --ptty +/dev/ttyT38-1 --route
> "modem:.*=sip:<dn>@192.168.20.245;OPAL-Force-Fax-Mode=true" --route
> "sip:.*=modem:<dn>"
>
>
> The remaining problem is that on the receiving end we only have the top
> centimetre or two of the image. I think this may be a tiff library issue
> but I'm not sure.
>
> Cheers
>
> Alex
>

In the end I had to disable ECM in the Hylafax modem definition for 
t38modem, this was what was causing the image truncation. Odd, because 
both t38modem and spandsp ostensibly support ECM. I'm wondering if I was 
sending audio out directly over TDM rather than via a SIP gateway using 
G.711 then ECM would be OK... probably a timing issue.

Cheers
Alex

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