Re: [sipcore] Why doesn't 4244bis cover Marianne's use-case?

Hadriel Kaplan <> Sat, 20 November 2010 14:43 UTC

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From: Hadriel Kaplan <>
To: "Worley, Dale R (Dale)" <>
Date: Sat, 20 Nov 2010 09:44:00 -0500
Thread-Topic: Why doesn't 4244bis cover Marianne's use-case?
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Subject: Re: [sipcore] Why doesn't 4244bis cover Marianne's use-case?
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The two aren't orthogonal - although perhaps we're talking about a different "draft-mohali".
I'm talking about draft-mohali-sipcore-reason-call-forwarding-00.

If you ignore the reason cause code stuff in it, the main functional difference I can discern in that draft is that the call-forwarding action occurs internally in a system, rather than externally with a SIP redirect/response.  If that's true, then what I was trying to say at the mic during the WG meeting was that we've already said H-I would record H-I entries for internal processing - essentially as if the SIP request had gone to a next-hop and the next-hop had redirected the call using 3xx, or rejected the call with a 4xx.

What we haven't settled on is, for entries created due to internal processing, whether the embedded Reason header cause code can still be used or not, and specifically whether we can use *SIP* response codes in that embedded Reason header for internally generated H-I entries.  Personally I think it makes sense to do so, because what matters in this whole thing is how the receiver of H-I processes H-I entries to invoke specific application logic.  It doesn't actually matter whether there was a physical on-the-wire SIP 486 response which caused a proxy to recurse or retarget - what matters is that the proxy retargeted due to the user being busy.

If you believe that, then the new cause codes in draft-mohali-sipcore-reason-call-forwarding-00 suddenly start to look a heck of lot like SIP reason codes.  For example, a "User Busy" is the same as a SIP 486; a "No Reply" is a SIP 408; a "deflection immediate response" is a 302; "Not Logged-in" is a 480.


On Nov 19, 2010, at 11:42 AM, Worley, Dale R (Dale) wrote:

> ________________________________________
> From: [] On Behalf Of Hadriel Kaplan []
> It was unfortunate that we ran out of time in sipcore to talk about Marianne's draft, because I think it's a kind of litmus test of rfc4244bis.  Or else I think I must be missing something very basic. (easily the case)
> _______________________________________________
> As others have said in other terms,  draft-mohali-diversion-history-info is orthogonal to 4244bis.  draft-mohali provides additional Reason values that provide more detailed information on why a call was routed as it was.  Those Reason values will be recorded in H-I according to 4244bis.  In a sense, draft-mohali *is* a litmus test of 4244bis, because without H-I, the value of the new Reason values would be dramatically reduced.  But since the two are orthogonal, draft-mohali needs to be specified, but it can be specified separately.
> Dale