[macro-normal]
exten => s,1,Dial(${ARG2}|15)
exten => s,2,Goto(s-${DIALSTATUS},1)
exten => s-NOANSWER,1,Voicemail(${ARG1},u)
exten => s-BUSY,1,Voicemail(${ARG1},b)
exten => s-CHANUNAVAIL,1,Voicemail(${ARG1},u)

But it doesnt go to chanunavail:

notmutt*CLI>
   -- Executing [44988@internal:1] Dial("SIP/44987-b7401ed0", 
"Zap/g1/44988") in new stack
   -- Requested transfer capability: 0x00 - SPEECH
   -- Called g1/44988
   -- Zap/1-1 is proceeding passing it to SIP/44987-b7401ed0
   -- Accepting call from '44987' to '44988' on channel 0/16, span 1
   -- Executing [44988@incoming:1] Macro("Zap/16-1", 
"normal|44988|SIP/44988") in new stack
   -- Executing [s@macro-normal:1] Dial("Zap/16-1", "SIP/44988|15") in 
new stack
   -- Called 44988
   -- Channel 0/1, span 1 got hangup
   -- Hungup 'Zap/1-1'
 == Everyone is busy/congested at this time (1:0/0/1)
 == Auto fallthrough, channel 'SIP/44987-b7401ed0' status is 'CHANUNAVAIL'
   -- Channel 0/16, span 1 got hangup request
 == Spawn extension (macro-normal, s, 1) exited non-zero on 'Zap/16-1' 
in macro 'normal'
 == Spawn extension (macro-normal, s, 1) exited non-zero on 'Zap/16-1'
   -- Hungup 'Zap/16-1'


Works for noanswer:

notmutt*CLI>
   -- Executing [44988@internal:1] Dial("SIP/44987-b7328220", 
"Zap/g1/44988") in new stack
   -- Requested transfer capability: 0x00 - SPEECH
   -- Called g1/44988
   -- Zap/1-1 is proceeding passing it to SIP/44987-b7328220
   -- Accepting call from '44987' to '44988' on channel 0/17, span 1
   -- Executing [44988@incoming:1] Macro("Zap/17-1", 
"normal|44988|SIP/44988") in new stack
   -- Executing [s@macro-normal:1] Dial("Zap/17-1", "SIP/44988|15") in 
new stack
   -- Called 44988
   -- SIP/44988-09598080 is ringing
   -- Zap/1-1 is ringing
   -- Nobody picked up in 15000 ms
   -- Executing [s@macro-normal:2] Goto("Zap/17-1", "s-NOANSWER|1") in 
new stack
   -- Goto (macro-normal,s-NOANSWER,1)
   -- Executing [s-NOANSWER@macro-normal:1] VoiceMail("Zap/17-1", 
"44988|u") in new stack
   -- <Zap/17-1> Playing 'vm-theperson' (language 'en')