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Re: [Sip] [RFC 4235 & draft-kuthan-sip-derive] 481 "Call doesn't exist" for initial SUBSCRIBE ?


On Oct 31, 2008, at 12:54 PM, Dale.Worley at comcast.net wrote:


  From: "=?UTF-8?Q?I=C3=B1aki_Baz_Castillo?=" <ibc at aliax.net>


In any case, for the purposes of DERIVE, none of that matters:
Any failure response to the SUBSCRIBE, or a NOTIFY that does not
list the call in question, results in call rejection.


  But this behaviour would deny calls from devices not supporting
  RFC4235 (receiving a SUBSCRIBE Event: dialog).AFAIK this draft says
  that if the SUBSCRIBE is replied with 200 thenthe dialog exists and
  identity verified, if 481 then the devicesupports RFC 4235 and it's
  a suspicius call, and for any other failureroute it could mean that
  the device doesn't support RFC 4235 or anykind of "protection" in
  an intermediary proxy. In the last case, thereceptor of the INVITE
  should choose to accept or deny the call, hecannot know if the
  sender is really the From (or if he is not).
clearly one needs a Supported option-tag in the initial request to let the called party know that it might be reasonable to try to RRC using DERIVE. 


--
Dean


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