[macro-oneline]
exten => s,1,Answer
exten => s,2,Wait(1)
exten => s,3,GotoIf($["${ARG1}" = "${CALLERIDNUM}"]?7:4)
exten => s,4,Dial(SIP/${ARG1},20,t)
exten => s,5,Goto(s-${DIALSTATUS},1)

exten => s-BUSY,1,Voicemail(b${ARG1})
exten => s-NOANSWER,1,Voicemail(u${ARG1})
exten => _s-.,1,Goto(s-NOANSWER,1)

exten => s,7,Answer
exten => s,8,VoicemailMain(${CALLERIDNUM})
exten => s,9,Hangup

[extensions]
exten => _1XX,1,Macro(oneline,${EXTEN})