exten => _1NXXNXXXXXX,1,Set(PEERCODECS=${SIP_CALLERPREFCODECS()})
exten => _1NXXNXXXXXX,2,Set(PREFCODEC=${CUT(PEERCODECS|:|1)})
exten => _1NXXNXXXXXX,3,Set(CODEC=${IF($[ ${PREFCODEC} = G723]?G723)})
exten => _1NXXNXXXXXX,4,Macro(dial,${BVOXTRUNK}${CODEC}/${EXTEN})