extentions.conf

[users]
; Internal
exten => _[1-6]X,1,NoOp()
same => n,Answer()
same => n,Dial(SIP/${EXTEN},,tT)
same => n,Hangup()

exten => 80,1,Answer()
same => n,Queue(main,cRt) ; c=Continue in dial plan ; R=Ring instead of moh when actually dialling ; t=Allow transfer by callee
same => n,Hangup()