RE: [Sipping] Re: draft-elwell-sipping-service-retargeting-00.txt

> Suppose A calls B. But B has forwarding on busy set (to C). 
> So the proxy 
> for B retargets, with the new R-URI being:
> 
> 	sip:c@example.com;
> 	    old-target=sip:b@example.com;
> 	    retargeting-reason=busy
> 
> This then goes to the proxy for C. It again has to retarget, 
> to one of 
> the registered contacts for C. This is a "normal" retargetting. What 
> does the draft expect the new R-URI to be? I can see at least three 
> possibilities:
> 
> 1.	sip:c-phone.example.com
> 
> 2.	sip:c-phone.example.com;
> 	    old-target=sip:b@example.com;
> 	    retargeting-reason=busy
> 
> 3.	sip:c-phone.example.com;
> 	    old-target=sip:c@example.com;
> 	    retargeting-reason=distribution
> 
> This is similar to the examples in the draft involving a deputy, but 
> where the address of the deputy is an AOR that requires 
> further routing. 
> If the human deputy that answers the phone is to get any value out of 
> this, it will be because his phone (sip:c-phone.example.com) 
> tells him 
> the situation. Only (2) above makes that work.
> 
> If that is what is intended, then proxy C must copy the 
> parameters from 
> the R-URI it receives to the new target. This is not standard 
> behavior 
> for a proxy.

Right: I wouldn't expect a proxy to "copy" parameters around. The whole
purpose of this draft is NOT to add new requirements on generic proxy.

Only the entity responsible for retargeting to a new SERVICE can modify
the target.

Personally, I think the best way to do this would be to have the first
retarget to point to:

sip:c@c-phone.example.com;old-target=sip:b@example.com;retargeting-reaso
n=busy

So it would avoid the "normal" routing steps afterwards, and the whole
problem
in the first place. I.e., don't use an AOR but a valid resolved contact.

That being said, if one is a masochist, you could decide to parse the
History-Info including the information (which I wouldn't do because it
is subject to be filtered out by "the network").

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