T38 Fax Receive

Asterisk Asterisk Support
1

Hello,

I’m trying to receive some T38 Fax from my DialPlan without using Hylafax.
I’m using the following DialPlan :

[fax_receive]
exten => _X.,1,Noop(Fax Reception)
same => n,Set(FAXFOLDER=/tmp)
same => n,Set(FAXSTREAM=${STRFTIME(,,%C%y%m%d%H%M)})
same => n,ReceiveFax(${FAXFOLDER}/${FAXSTREAM}.tif,f)
...

And when a Fax is coming, there is a reception error :

WARNING[29373][C-00000012]: app_fax.c:442 transmit_audio: channel 'SIP/XB4-N5-00000012' refused to negotiate T.38

WARNING[29373][C-00000012]: app_fax.c:224 phase_e_handler: Error transmitting fax. result=13: Unexpected message received.
WARNING[29373][C-00000012]: app_fax.c:833 transmit: Transmission failed

The incoming fax is just a scan from a printer using the PSTN. My provider is using T38-passthrough. Is it possible to force transcoding into T38 when the fax is coming ? Any idea of what does the “Unexpected message received” exactly means ? How can I overcome this transcoding ?