Re: [Sipping] Re: psychic early media behavior

[Dale.Worley at comcast.net]

   From: "Ejzak, Richard P (Richard)" <ejzak at lucent.com>

   Your scheme attempts to prohibit a UAC/network from denying early
   media unless the UAS supports the extension and allows it.

Um, well, no.  The point of the scheme is that if some combination of
the UAS/UAC/network would deny early media (absent the correct
negotiation to activate it), and the UAS or UAC is incapable of being
notified of that fact (because it does not support the right
extension), then the call would not complete to begin with due to 420
or 421.

This satisfies Paul's complaint -- If a pure-3261 UA can make a
connection, then early media will work.

My guess is that it probably works in all cases that TISPAN cares
about, because TISPAN is concerned about UAs supplied by the network
operators who need to regulate early media, and those UAs (we can
assume) implement the extension, and know how to negotiate regarding
early media.

The real problem comes in situations where one or both UAs don't
understand the extension, but early media aren't actually required in
for the call.  Can we devise a scheme which allows the bulk of these
calls to succeed?

Dale

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