DP: 掛斷時傳回指定的 SIP response code

範例：

exten => s-BUSY,1,Noop(Dial failed due to trunk reporting BUSY - giving up)
;
;exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 404 'Not Found' to the caller)
;exten => s-BUSY,n,Hangup(1)
;
;exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 403 'Forbidden' to the caller)
;exten => s-BUSY,n,Hangup(21)
;
;exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 603 'Declined' to the caller)
;exten => s-BUSY,n,Hangup(26)
;
;exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 502 'Bad Gateway' to the caller)
;exten => s-BUSY,n,Hangup(27)
;
;exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 484 'Address incomplete' to the caller)
;exten => s-BUSY,n,Hangup(28)
;
; exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 500 'Server internal failure' to the caller)
exten => s-BUSY,n,Hangup(38)
;
; exten => s-BUSY,n,Noop(Hangup the call and Return SIP response 503 'Service unavailable' to the caller)
exten => s-BUSY,n,Hangup(42)