From: "Emily Smith" <[EMAIL PROTECTED]>
I am new to the list and relatively new to SIP as well. I have a
question I hope someone can answer here. I have searched the SIP
RFCs and drafts to no avail.
It's subtle -- the problem is that the question you state has no one
answer. The deeper problem is that you say "performs a blind
transfer", but that operation has a number of steps. Usually,
X sends a REFER to Y,
Y sends 202 to X,
Y sends an INVITE to Z,
Z sends 200 to Y,
Y sends NOTIFY containing the 200 to X,
Y sends BYE to X,
X sends 200 (NOTIFY) and 200 (BYE) to Y.
One you focus on the fact that a "blind transfer" is a complicated
series of actions, you see that "a re-INVITE is valid up until the
dialog is ended". If the re-INVITE is sent from X to Y, it is
acceptable to Y until Y sends BYE to X. If the re-INVITE is send from
Y to X, it is acceptable to X until it receives the BYE from Y. If
the re-INVITE is accepted, it is followed by 200 and ACK. If the
re-INVITE is rejected (because the dialog has been terminated), it is
followed by 481 and ACK.
Since party X is on-hook at the time [...]
Only if the transfer has succeeded at this point, and the other end
has sent a BYE to terminate the dialog, or the user at this end has
hung up, leaving the UA to finish the transfer sequence.
Dale
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