On Fri, 2006-03-24 at 11:02 -0500, Paul Kyzivat wrote:
> Does the phone have to say what is happening? In the general case you
> cannot know this. Requiring that would limit future flexibility. If you
> want to say something, you say something vague related to what you know
> you have been asked to do ("reconnecting to ABC").
I've thought that a UA, when it changes the "far end" of a dialog (due
to REFER, INVITE w/Replaces, etc.), or changes the destinations of its
media streams, should provide some sort of in-band indicator to the
user, so that the user knows that he may be communicating with a
different person than before.
As for providing an explanatory message, perhaps there should be a
header for conveying this information. But there are inherent security
problems -- There is no way for the recipient of a REFER to know whether
the sender is actually carrying out the operation its explanatory header
claims it is. (And since I am assuming a malicious agent, confining
legitimate agents to carrying out only defined and specified call
control operations will not help.)
Dale
---
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