Something

[proc-fax]
exten => s,1,NoOp(Fax Detected To ${ARG1})
exten => s,n,Set(LOCALSTATIONID=Callweaver FAX)
exten => s,n,Set(LOCALHEADERINFO=Fax Termination)
exten => s,n,Set(FAXFILE=/tmp/${UNIQUEID}.tif)
exten => s,n,SipDTMFMode(inband)
exten => s,n,Set(SIP_CODEC=ulaw)
exten => s,n,Set(LOCALSTATIONID=Callweaver FAX) 
exten => s,n,Set(LOCALHEADERINFO=Callweaver Fax Termination)
exten => s,n,RxFAX(${FAXFILE},ecm)
exten => s,n,NoOp(RxFAX completed)
exten => s,n,NoOp(RX: REMOTESTATIONID is ${REMOTESTATIONID})
exten => s,n,NoOp(RX: FAXPAGES is ${FAXPAGES})
exten => s,n,NoOp(RX: FAXRESOLUTION is ${FAXRESOLUTION})
exten => s,n,NoOp(RX: FAXBITRATE is ${FAXBITRATE})
exten => s,n,NoOp(RX: PHASEESTATUS is ${PHASEESTATUS})
exten => s,n,NoOp(RX: PHASESTRING is ${PHASEESTRING})
exten => s,n,Hangup()

[myfax]
exten => 800,1,Goto(faxin,s,1);
exten => 801,1,Goto(faxout,s,1);
exten => 802,1,Goto(detectfax,s,1);

exten => 1000,1,Proc(fax,${EXTEN})
exten => 1001,1,Proc(fax,${EXTEN})