Discussion List for Freenum/ITAD Subscriber Number (ISN) Project

   From: 

 (John R Covert)

   2. the standard that the "0" extension always gets you to some
      sort of informational message about what to dial, or to an
      IVR of some sort, or to a human attendant.

Interestingly, assuming that the "real" extensions are at least 2
digits, it's not hard to use another NAPTR record to map extension 0
to an arbitrary SIP user-part.  Copying from someone else's example:

*.765               IN  NAPTR 100      10      "u"     "E2U+sip" \
                
"!^\\+*([^\\*][^\\*][^\\*]*)!sip:\\!"
 .
*.765               IN  NAPTR 100      10      "u"     "E2U+sip" \
                
"!^0$!sip:!"
 .

Dale