No subject

  ISUP Cause value                        SIP response 
  ----------------                        ------------ 
  1  unallocated number                   404 Not Found 
  2  no route to network                  404 Not found 
  3  no route to destination              404 Not found 

But if Asterisk does:

  exten => XXX,1,Dial(SIP/non_existing_peer)

it replies:

  SIP/2.0 503 Service Unavailable
  ...
  X-Asterisk-HangupCause: No route to destination
  X-Asterisk-HangupCauseCode: 3

Why not a 404 as RFC 3398 suggests?
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 file - 06-10-08 08:08  
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That auto fallthrough will call Congestion on the channel and send 503
Service Unavailable. 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
06-10-08 08:08  file           Note Added: 0088523                          
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