exten => 4802124336,1,ChanIsAvail(SIP/7000,sj)
exten => 4802124336,2,Dial(SIP/7007,20,tT)
exten => 4802124336,3,Voicemail(u7007@defualt)
exten => 4802124336,4,Hangup
exten => 4802124336,102,Goto(3)