[Freeswitch-users] Commercial Fax over T.30 for FreeSWITCH

Steve Underwood steveu at coppice.org
Thu May 3 18:56:35 MSD 2012

Hi Anita,

What are you hoping to get from a commercial solution? You won't get 
improved reliability. If you go with the Digium solution support seems 
to be limited to an offer of a refund. I have helped a number of FAX for 
Asterisk users move to spandsp to improve their performance.

What are you actually doing? Are you simply sending and receiving FAXes 
on a Sangoma E1 card? If that gives you anything less than 99.5% 
success, something is wrong in your setup. A timing problem with the E1 
is the most likely cause. Not the motherboard or the kernel. The E1 
interface itself. You MUST make the PSTN the source of the clock for the 
E1. If you make your card the source you WILL have serious problems with 

Using T.38 gateway operation to interwork between the PSTN and VoIP can 
give additional problems, as some system do strange things with the 
signaling, or don't open the right ports when the call switches from RTP 
to UDPTL. If those things are sorted out, and your IP interface is not 
losing lots of packets, you should have few failures.


On 05/03/2012 08:23 PM, Anita Hall wrote:
> Hi Alex
> Thanks for the tip :)
> No, I am running FreeSWITCH on an Ubuntu 64-bit Quad core machine. 
> There is no VM.
> Is it possible to use Hylafax instead of or in combination to 
> FreeSWITCH if I am using Sangoma E1 Cards ?
> What all things should I check to ensure that the timing on my system 
> is good? Like, may be, my motherboard is bad or my kernel could be 
> tuned better ?
> Cheers!
> regards,
> Anita
> On Thu, May 3, 2012 at 1:55 PM, Alex Crow <acrow at integrafin.co.uk 
> <mailto:acrow at integrafin.co.uk>> wrote:
>     On 03/05/12 08:08, Anita Hall wrote:
>     > Hi
>     >
>     > I am looking for a commercial product for Incoming Fax over T.30 for
>     > FreeSWITCH.
>     >
>     > Like Commetrex is available for Asterisk, is there something for
>     > freeswitch ?
>     >
>     > regards,
>     > Anita
>     >
>     Hi,
>     I use Hylafax with T38Modem (and gateway to T.30 in Freeswitch).
>     Hylafax
>     is as good as any commercial product, and I get at least 99.5% success
>     using it with onboard analog modems. I've not sent or received
>     hundreds
>     of faxes over T38modem but I don't see why it should be any worse.
>     Just one question - are you running Freeswitch on a VM? Fax is very
>     timing critical and I found running on a VM caused an awful lot of
>     failures for T.30.
>     For outbound:
>     <extension name="faxout">
>     <condition field="ani" expression="^t38modem.*$"/>
>     <condition field="destination_number" expression="^(9\d{6,14})$">
>     <action application="set" data="absolute_codec_string=PCMU"/>
>     <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/gateway/isdngw/$1"/>
>     </condition>
>     </extension>
>     For inbound:
>     <extension name="faxin" >
>     <condition field="network_addr" expression="<ip address of isdngw>"/>
>     <condition field="context" expression="default"/>
>     <condition field="destination_number" expression="^100([0-4])$">
>     <action application="bridge" data="{sip_execute_on_image='t38_gateway
>     self nocng'}user/t38modem$1@${domain_name}"/>
>     </condition>
>     </extension>
>     Cheers
>     Alex

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