[asterisk-users] T.38 gateway ATA

[Jeff LaCoursiere]

On 09/25/2012 09:26 AM, Bryant Zimmerman wrote:
> Jeff
>
> Can you please clarify your layout? If you have an asterisk 1.8 (I 
> would use 10 for this if possible) server why can't you just take the 
> gateway call on that via a sip trunk. If you are coming in from and 
> land line and want to do t.38 to the asterisk 1.8 server you would 
> need a FXO t.38 gateway. Based on your description I am not sure what 
> your sources are and what your final desired destination is. Please be 
> specific with your response.  We do t.38 all the time and have great 
> success with it but the success is in the setup and control of the 
> endpoints (gateways and ATAs)
>
> Thanks
>
> Bryant Zimmerman (ZK Tech Inc.)
> 616-855-1030 Ext. 2003
>
>
> ------------------------------------------------------------------------
> *From*: "Jeff LaCoursiere" <jeff at sunfone.com>
> *Sent*: Monday, September 24, 2012 9:20 PM
> *To*: "Asterisk Users Mailing List - Non-Commercial Discussion" 
> <asterisk-users at lists.digium.com>
> *Subject*: [asterisk-users] T.38 gateway ATA
>
>
> Hoping for some clarification. I would like to setup a NORMAL (not
> T.38) fax machine on an ATA, and have the ATA be a T.38 gateway to a
> remote asterisk (1.8) server, which is doing T.38 relay (passthru) to a
> provider.
>
> Some amount of googling today seems to imply that most ATAs are just
> T.38 passthru devices, and expect a T.38 capable fax machine, otherwise
> just fallback to ulaw (and mostly fail, in my experience so far).
>
> So does anyone use an ATA that actually does the gateway transcoding to
> a normal fax machine? Or am I barking up the wrong tree?
>
> Thanks!
>
> j
>
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Hi Bryan,

To follow an inbound fax call, our intended setup would be:

Our upstream sends a T.38 call to our border asterisk (1.8) server, 
which creates another T.38 call to the customer's hosted asterisk (1.8) 
instance, which creates another T.38 call to the ATA, which is over the 
Internet to their location.  The ATA would do the transcoding (is that 
even the appropriate term in this case?) to T.30, to the FXS connected 
normal fax machine.

Its that last bit that I am having trouble confirming is a feature of 
any mainstream ATA.  When I dug into it yesterday it seems that the 
mainstream ATAs will passthru T.38, expecting the connected fax machine 
to work with T.38 natively.  I can't depend on that.  The asterisk 
servers are all remote, and though I could presumably do the gateway on 
the asterisk server I would then have a ulaw fax call over the internet 
to the ATA, which in my experience has not been very reliable.

Of course I will need outbound faxing to follow the reverse path, 
letting the ATA turn the T.30 outbound fax call into T.38, which travels 
through our various asterisk servers to the upstream provider...

So in a nutshell, is there anyone using an ATA as the *gateway* rather 
than passthru?  I feel I am still not being clear... does that help?

Thanks,

j
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