[from_sbc]
exten => _.,1,SET(GET_TRANSFERRER_DATA=*)
same => n,Set(DN=${SIP_HEADER(TO):5})
same => n,Set(DN=${CUT(DN,@,1)})
same => n,Set(VIA=${CUT(CUT(SIP_HEADER(Via), ,2),:,1)})
same => n,Verbose(1,${HASH(TRANSFER_DATA,Refer-To)})
;same => n,HASH(TRANSFER_DATA,X-That-Special-Header)