[macro-dial_ext]
exten => s,1,Dial(Sip/${ARG1},20,r)
exten => s,101,Voicemail(sb${ARG1})
exten => s,2,GotoIf($["${DIALSTATUS}"="BUSY"]?s-BUSY,1)
exten => s,3,Voicemail(su${ARG1})
exten => s-BUSY,1,Voicemail(sb${ARG1})