Holger Schmidt wrote:
Dear all,
I am sending multiple successive MESSAGE requests to the same SIP-UA. Do
I have to change the Call-ID header for the MESSAGE requests or do I
have to send the same Call-ID header for all the MESSAGE requests?
Is there a general rule for MESSAGE request when to change the Call-ID
header?
Call-ID is used (together with the To-tag and From-tag) to identify a
dialog. If your MESSAGE requests are being sent within a dialog then
they must carry the callid of the dialog. If they are being sent outside
a dialog then a Call-ID is unnecessary and inappropriate.
If you have a dialog, then I think it is ok to send MESSAGEs within it
if they are related to the dialog. But it is not considered acceptable
to establish a dialog for the purpose of establishing a session for
sending MESSAGEs. (Yes, I know that some widely deployed products do
this, but that doesn't make it right.) That is session mode messaging,
and MSRP has been defined for that purpose.
Paul
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