Mother

exten => s,1,LookupCIDName
exten => s,2,Macro(record-on,IN,${CALLERIDNUM})
exten => s,3,Dial(${A}&${B},15,tm)
exten => s,4,Wait(1)
exten => s,5,Dial(${A}&${B}&${C},15,tm)
exten => s,6,Wait(1)
exten => s,7,Dial(${A}&${B}&${C}&${D},15,tm)
exten => s,8,Wait(1)
exten => s,9,Dial(${A}&${B}&${C}&${D}&${E},15,tm)
exten => s,10,Hangup

; A & B are busy...
exten => s,104,Dial(${C},15,tm)
exten => s,105,Wait(1)
exten => s,106,Dial(${C}&${D},15,tm)
exten => s,107,Wait(1)
exten => s,108,Dial(${C}&${D}&${E},30,tm)
exten => s,109,Hangup

; C is busy...
exten => s,205,Dial(${D},15,tm)
exten => s,206,Wait(1)
exten => s,207,Dial(${D}&${E},45,tm)
exten => s,208,Hangup

; D is busy...
exten => s,306,Dial(${E},60,tm)
exten => s,307,Hangup

; E is busy...
exten => s,407,Answer
exten => s,408,Wait(1)
exten => s,409,Playback(unavailable)
exten => s,410,Hangup