From: [EMAIL PROTECTED]

   Why this peer-to-peer relationship is not considered as a dialog?

The basic answer is "Because RFC 3261 says it isn't."

A dialog has a call-id, to-tag, etc.  The creation of a dialog sets
the contacts and route-set.  But the big difference is *functional*.
That data allows: (1) later requests sent by the caller will not fork
and will take the path established by the first request, and (2) the
callee can send requests to the caller.

A REGISTER does not establish a dialog, but a sequence of REGISTERs
with the same call-id are processed by the recipient in ways that
resemble some of the processing that is done in dialogs.  Especially,
requests with higher CSeq are assumed to supersede requests with lower
CSeq.  So it is convenient to refer to these sequences of messages as
"pseudo-dialogs".

(If you are implementing this, make sure you read and understand the
rules in RFC 3261 section 10.3.  The rules are more complex than can
be easily remembered.)

The PUBLISH request does not establish a dialog, either, but PUBLISH
requests are not considered related if they have the same Call-Id, so
there is no use talking about pseudo-dialogs with them.

Dale
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