-------------------------------------------   Add this piece in extensions.conf
[faxout]
exten => s,1,Set(FAXFILE=/tmp/test3_opbx_rulez.tif)
exten => s,n,TxFAX(${FAXFILE}|caller|debug)
exten => h,1,NoOp(TX: REMOTESTATIONID is ${REMOTESTATIONID})
exten => h,n,NoOp(TX: PHASEESTATUS is ${PHASEESTATUS})

------------------------------------------- create a file with this content somewhere.

Channel: SIP/800@aretha.navynet.it

MaxRetries: 0
WaitTime: 30

;Set: T38CALL=1
Set: LOCALSTATIONID=Fulgas
Set: LOCALHEADERINFO=OpenPBX on BSD

Context: faxout
Extension: s
priority: 1