fax interception asterisk

extensions.conf

; set dahdi-channels.conf's fax line to use this context
[fax-intercept]
  include => from-internal
  ; expects "immediate=yes" on dahdi line
  exten => s,1,Answer()
   ; emulate dialtone while reading the number being dialed
    same => n,ReadExten(FAXOUT,dial,${CONTEXT},i,30)
    same => n,Verbose(10,Dialing fax to ${FAXOUT})           
    same => n,Ringing()                                      
  ; It takes ~ 4 seconds to dial a 10 digit number from the fax
    same => n,Wait(5)
  ; normal calls continue here
    same => n,GoTo(${CONTEXT},${FAXOUT},1)
 
  ; fax interception - dahdi hijacking the call starts here
  exten => fax,1,Verbose(5,Sending fax to ${FAXOUT})
   same => n,Verbose(10,**** FAX RECEIVE ****)
   same => n,Set(__FAXFILE=outgoing-${FAXOUT}-${STRFTIME(,,%C%y%m%d%H%M)}.tif)
   same => n,Verbose(10,**** SETTING FAXOPT ****)
   same => n,Set(FAXOPT(ecm)=yes)
   same => n,Set(FAXOPT(maxrate)=14400)
   same => n,Set(FAXOPT(minrate)=2400)
   same => n,Verbose(10,FAXOPT(ecm) : ${FAXOPT(ecm)})
   same => n,Verbose(10,FAXOPT(headerinfo) : ${FAXOPT(headerinfo)})
   same => n,Verbose(10,FAXOPT(localstationid) : ${FAXOPT(localstationid)})
   same => n,Verbose(10,FAXOPT(maxrate) : ${FAXOPT(maxrate)})
   same => n,Verbose(10,FAXOPT(minrate) : ${FAXOPT(minrate)})
   same => n,Verbose(10,**** FAX RECEIVE FILE : ${FAXFILE} ****)
   same => n,ReceiveFAX(/var/spool/asterisk/fax/${FAXFILE})
   same => n,Hangup()

  exten => h,1,Verbose(10,**** FAX RECEIVE COMPLETE ***)
   ; This needs to be global otherwise the Originate context doesn't know the fax filename
   same => n,Set(GLOBAL(FAXFILE)=${FAXFILE})
   same => n,GoToIf(Len(${FAXFILE})>0?RelayFax:FaxHangup)
   same => n(RelayFax),Verbose(10,Relaying fax to ${FAXOUT})
   ; send this to the upstream PBX that actually has a SIP trunk to the PSTN
   same => n,Originate(SIP/${FAXOUT}@UPSTREAM_PBX,exten,fax-relay,start,1)
   same => n,Verbose(10,Originate status ${ORIGINATE_STATUS})
   same => n(FaxHangup),Verbose(10,Hanging up on Fax)
   same => n,Hangup()

[fax-relay]
  exten => start,1,Verbose(10,*** FAX RELAY ***)
   same => n,Verbose(10,Fax file is ${FAXFILE})
   same => n,SendFax(/var/spool/asterisk/fax/${FAXFILE})
   same => n,Verbose(10,Fax relay status: ${FAXSTATUS})
  exten => h,1,Verbose(10,(Reached hangup fallthrough)
   same => n,Hangup