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

[Clemens Ebentheuer]

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