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

[Alex Crow]

Brian,

I am *not* going out to/in from the world at large from/to the FS box 
via T38. I don't have a T38 capable gateway at the moment, and this is 
for an emergency box to replace a machine with several analog modems 
attached to the Mitel PBX.

Therefore I have to translate t38modem's T38 I/O into audio over SIP to 
send to/rcv from our (non-T38-understanding) Mitel PBX which connects 
via E1 trunks to the PSTN.

I know it's not ideal but it does seem to work OK so far.

We have an older fax server (analog lines) where the modem does not 
support ECM. We virtually never have any problems sending or receiving 
faxes from this machine. However if you or anyone else can help get ECM 
working in this setup I'd be happy, but I have my doubts due to the 
G.711 step between the FS machine and the Mitel, probably causing jitter.


To clarify, here is the topology:

Hylafax<---Audio---->t38modem<---T38--->Freeswitch/t38gateway<----G.711/SIP--->Mitel 
3300(T38 unsupported, grr)<---ISDN30---->PSTN

I have to do the transcode as the Mitel is the weak link.

If I could pop an E1 card in the FS box I'm sure things would work a lot 
better, but we don't have a spare card or indeed a spare circuit right now!

Hope this make sense....

Alex



On 11/11/11 16:18, Brian West wrote:
> Disabling ECM by FAR the WRONG thing to do and you have this mindset 
> that is required its only required when you were hanging on by a 
> thread doing G.711 Faxing over the public internet and you didn't want 
> one tiny blip to screw the fax over.  I still don't understand why 
> Alex is doing t.38 gateway from audio to t.38?  Either way ECM works 
> fine never had any issues with it.
>
> /b
>
> On Nov 11, 2011, at 9:32 AM, Steve Underwood wrote:
>
>> Turning off ECM is equivalent to saying "I use FAX, but I couldn't give
>> a damn if they are received".
>>
>> Steve
>>
>>
>> On 11/11/2011 09:51 PM, Tihomir Culjaga wrote:
>>> always disable ECM for fax calls over IP... its the 1st rule of thumb
>>> for VoIP faxing :=)
>
>
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