[safedial]
exten => _X.,1,Dial(SIP/peer/${EXTEN})
exten => _X.,2,Goto(check_dialstatus,ds-${DIALSTATUS},1)

[check_dialstatus]
exten => ds-CANCEL,1,Hangup
exten => ds-ANSWER,1,Hangup
exten => ds-NOANSWER,1,Hangup
exten => ds-BUSY,1,Busy
exten => ds-CHANUNAVAIL,1,Congestion
exten => ds-CONGESTION,1,Congestion
exten => ds-,1,Congestion
exten => _ds-.,1,Congestion

[mobile]
exten => _04XXXXXXXX,1,Goto(safedial,${EXTEN},1)