Nina Garaca wrote:
Hi All,
I have some questions regarding 1xx responses that establishes dialog
(with To tag) .
Q1: Should I expect that these responses have a Contact header?
Yes. If it doesn't then it hasn't provided enough information to
establish the dialog.
Q2: If they do so, should the remote target of the dialog be refreshed
by that Contact at the side that has received that 1xx response and
should the remote target of the dialog be refreshed by the Contact in
the INVITE request at the side that has received that INVITE?
Wel, the first response isn't really a "refresh" since until then you
don't have one to refresh. I suppose if the address were to change
before the completion of the INVITE transaction then it *could* be
refreshed in subsequent 1xx responses. But unless you are using reliable
provisionals that is problematic, since you don't know if the
provisionals have been received. One would hope that this situation will
not arise.
Regarding the UAS, I don't understand the question. It receives the
initial INVITE, which contains the contact from the UAC. That is the
only one it gets. In an initial INVITE there is no question of
"refreshing". In the case of a reINVITE, the value is a "refresh", and
it doesn't take effect (refresh) until and unless it successfully
completes. (I believe there is some degree of controversy over this last
point.)
Paul
Q3: If not, should the remote target of the dialog be refreshed by the
Contact in the INVITE request
at the side that has received that INVITE and has sent dialog
establishing 1xx response?
Thanks in advance.
Best Regards
Nina.
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