FreePBX custom conferrence System

nano /etc/asterisk/extensions_custom.conf

[from-internal-custom]

exten =>_0280900374,1,Set(GLOBAL(LOOPCOUNT)=1)
same=>n,Read(conf,entering-conf-number)
same=>n,Set(LOOPCOUNT=$[${LOOPCOUNT} + 1])
same=>n,verbose(value of ${LOOPCOUNT})
same=>n,GotoIf($[${LOOPCOUNT} > 3]?hangup)
same=>n,goto(ext-meetme,${conf},1)
same=>n(hangup),Playback(im-sorry&goodbye)
same=>n,Hangup()
exten=>i,1,Goto(from-internal-custom,_0280900374,2)


nano /etc/asterisk/extensions_override_freepbx.conf

[ext-meetme]
exten=>i,1,Playback(im-sorry)
exten=>i,2,goto(from-internal-custom,0280900374,2)

then we can do  misc destination mapping to the 0280900374 and point our inbound route to that misc desc