Subject: RE: [Sipping] Does 'isfocus' indicate capability or behavior?

From: "Even, Roni" <[email-masked]>
Date: Fri, 28 Jan 2005 17:45:16 +0200

Aki,
I think that I see two cases for your question.
1. A UA gets a refer from another UA and does not know if it is a
conference or a point to point call. The UA can always send an OPTION to
figure out if it is a conference.
2. A end user device like a phone or video conferencing end point that
has mixing capabilities. The question is if this EP will have one URI
for both point to point calls or multipoint calls. Even if it has one
URI my thinking is that it shall always indicates the isfocus
functionality if it allows other users to use its mixing function. If it
only allows conferences to be created by the user that owns the device
then it should send the isfocus only when it is running in the mixing
mode.
Roni Even 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Aki Niemi
Sent: Friday, January 28, 2005 10:01 AM
To: sipping
Subject: [Sipping] Does 'isfocus' indicate capability or behavior?

Hi,

I recently encountered a problem related to conferencing, and more 
specifically to the use of the isfocus callee capability.

Currently, I believe the 'isfocus' callee capability tells the other end

that the UA is a focus and will mix together all calls made to that 
contact URI. But does the absence of 'isfocus' indicate the opposite? 
This is where I think there is some ambiguity, i.e., does it indicate 
*capability* or currently active *behavior* only.

The problem is that a UA receiving an invitation should be able to 
determine whether the invitation is to a conference, or to a one-to-one 
call. I can imagine the pop-up window being different for each case, 
maybe even the UA software client. This determination is probably meant 
to be based on the 'isfocus', and whether it is true or false.

On the other hand, since 'isfocus' is a callee capability, it could be 
interpreted to mean that the UA can act as a focus, but isn't doing so 
at the moment. Meaning a focus-capable UA would include it in all
INVITEs.

Or do we need a new callee-cap for that, named 'mayfocus'? Or instead of

binary have the 'isfocus' callee capability have three states, {active, 
inactive, false}?

Cheers,
Aki

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_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
Use [email-masked] for new developments of core SIP