Re: [Sip] RE: Identity after reinvite

Cullen Jennings wrote:
> On 11/16/04 12:05 AM, "Jonathan Rosenberg" <jdrosen@cisco.com> wrote:
> 
>>The solution, which rfc3261 warns of, is that a UA has to put its actual
>>identity in the From field URI, not what it saw in the To field of the
>>original request. This will break all compatibility with rfc2543, but
>>will work with other rfc3261 compliant endpoints, since the URI is no
>>longer used for dialog identification.
> 
> At this point, I really see two paths forward for the connected party
> problem.
> 
> 1) We do as suggested above and allow everything in the From and To other
> than the tags to be changed in a Re-INVITE or UPDATE.
> 
> 2) We create a new thing that is like invite with replaces but add a new tag
> that is called say "subsumes". So if A and B have a dialog, or early dialog,
> and one of them wants to change a From. The UA sends an INVITE for a new
> dialog, indicates it replaces the old dialog, and indicates that it subsumes
> it. The subsumes flag would mean that any existing media session, qos
> reservations, etc did not change and got moved to the new dialog. 

I vote for biting the bullet and changing From/To. It will initially 
cause some pain, but it will solve a number of problems in a clean way.

We could define an option to be announced in Supported that indicates 
ability to do this. Could end up with:

	INVITE ...
	To: sip:bob@biloxi.com
	From: sip:alice@atlanta.com;tag=alice
	Supported: to-from-change
	Identity: aaaaaaaa (signed over From)
	Identity-Info: https://atlanta.com/cert
	...

	180 ...
	To: sip:charlie@chicago.com;tag=charlie
	From: sip:alice@atlanta.com;tag=alice
	Supported: to-from-change
	Identity: cccccccc (signed over To)
	Identity-Info: https://chicago.com/cert
	...

	200 ...
	To: sip:charlie@chicago.com;tag=charlie
	From: sip:alice@atlanta.com;tag=alice
	Supported: to-from-change
	Identity: cccccccc (signed over To)
	Identity-Info: https://chicago.com/cert
	...

	ACK ...
	To: sip:charlie@chicago.com;tag=charlie
	From: sip:alice@atlanta.com;tag=alice
	Supported: to-from-change
	Identity: aaaaaaaa (signed over From)
	Identity-Info: https://atlanta.com/cert
	...

	UPDATE ...
	To: sip:alice@atlanta.com;tag=alice
	From: sip:charlie@chicago.com;tag=charlie
	Supported: to-from-change
	Identity: cccccccc (signed over From)
	Identity-Info: https://chicago.com/cert
	...

	200 ...
	To: sip:alice@atlanta.com;tag=alice
	From: sip:charlie@chicago.com;tag=charlie
	Supported: to-from-change
	Identity: aaaaaaaa (signed over To)
	Identity-Info: https://atlanta.com/cert
	...

(Above shown as they look to receiving UA.)

	Paul

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