exten => s,n,MixMonitor(${CALLDIR}${CALLFILENAME}.${MIXMON_FORMAT})
exten => s,n,Dial(SIP/${CALLNUMBER}, 30, A(beep)g)
exten => s,n,StopMixMonitor()
exten => s,n,System(mv ${CALLDIR}${CALLFILENAME}.${MIXMON_FORMAT} ${CALLDIR}${SESSION_ID}.${MIXMON_FORMAT})
== Spawn extension (call-center-transfer/n, Local/101, 1) exited non-zero on 'SIP/749XXXXXXX-0000aae7'
[2018-03-23 09:53:02]
WARNING[61008][C-0000594f]: pbx.c:6863 __ast_pbx_run: Channel 'SIP/749XXXXXXX-0000aae7' sent to invalid extension but no invalid handler: context,exten,priority=call-center-transfer/n,Local/101,1