[Freeswitch-users] t38_gateway self - no re-Invite?

Anthony Minessale anthony.minessale at gmail.com
Sat Feb 26 01:24:39 MSK 2011


have you tried the self vs peer args to the t38 gateway app, maybe you
have it configured backwards.


On Fri, Feb 25, 2011 at 4:11 PM, Clemens Ebentheuer <ce at kapper.net> wrote:
> Hi,
>
>> It can be, that in your case the device is simply detecting the FAX
>> tones itself before FS does. When the device sends a ReINVITE to FS FS
>> has no chance to detect CNG anymore and hence never switch to t38.
>
> Maybe you´re right here - or zoiper (http://www.zoiper.com/softphone/classic/ which is a softphone with only t38 fax support [no g711 fallback]) sends the reinvite every time after answer when it is sending a fax.
>
>>
>> Just trace the sending FAX-Device for SIP-Signalling and you should se
>> a
>> ReINVITE from FAX-device to FS, if this is true.
>
> Here is a debug with siptrace: http://pastebin.freeswitch.org/15439
>
> If I read the logs in a right way:
> then FS executes t38_gateway on answer -
> sends a 200 OK to zoiper -
> zoiper answers with ACK and then reinvites with t38 -
> FS answers 100 Trying-
>
> And nothing is happening. I´m not sure if this is the scenario you describe below, but shouldn´t FS answer with a t38 sdp so zoiper knows where to send it´s t38 fax??
>
>>
>> You should check your t38-Device configuration. See if it is able to
>> let
>> the t38 fax detection job only by FS.
>>
>> Establish a call from the Fax device to a phone. Can your hear the CNG
>> signal when you pickup the phone? Does it suddenly stop? If so, the FAX
>> device or FS/mod_spandsp has sent a t38-ReINVITE.
>>
>> Do you see something like "media Bug removed" in FS console (DEBUG
>> level) after 20 seconds of listening to 1100Hz? If so, then FS failed
>> to
>> detect CNG, hence it never received it (or for too short to detect it).
>>
>> On my Grandstream ATAs this wasn't possible, so I had to search for a
>> hack.
>>
>> Hope this will light up your problems a little bit.
>>
>>
>> > If so, I´m wondering why rxfax in t38 mode is working fine then -
>> with re-invite.
>> Can't tell you with this, never tried that. sorry.
>
> Thx,
>
> clemens
>
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-- 
Anthony Minessale II

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