Re: [sipcore] H-I in 100 response (was REMINDER: Re: WGLC: draft-ietf-sipcore-rfc4244bis)

Ian Elz <> Wed, 03 November 2010 09:50 UTC

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Date: Wed, 03 Nov 2010 09:50:34 +0000
From: Ian Elz <>
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Subject: Re: [sipcore] H-I in 100 response (was REMINDER: Re: WGLC: draft-ietf-sipcore-rfc4244bis)
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02 November 2010 22:19:38 Paul Kyzivat wrote:

>On 11/2/2010 4:31 PM, Elwell, John wrote:
>> So the remaining issue from this thread concerns whether to mandate 
>>History-Info in a all provisional responses or just non-100 provisional 
>>responses (subject to presence of the option tag in the request). Given that 100 
>>tends to be generated differently from other provisional responses, and given 
>>the marginal use of H-I in 100 responses, I would prefer either to omit H-I from 
>>100 responses or use MAY. I don't have a strong opinion, but perhaps others have 
>>a view.

>Requiring (even permitting) H-I in 100 responses is a *terrible* idea.

>I don't see why you would need H-I in *any* provisional responses (with 
the possible exception of 199.)

(>Disclaimer - I have not read all the discussion on this subject.)

>    Thanks,
>    Paul

I don't believe that you can stop H-I in all provisional responses. 

I don't think that H-I is useful in a 100 Trying response but it adds 
significant value to other 1xx responses. I believe that 3GPP have specified H-I 
in 181 Call is Being Forwarded responses as part of the CDIV service.

Subject to Privacy settings returning the H-I in the 181 provides valuable 
information to the caller.

Ian Elz

{I have been trying to follow all the threads relating to 4424bis but no longer 
being employed in telecoms means that I have limited time. I was going to review 
the 4424bis draft but then as there were lots of other commnets I have sat back 
and and lurked. Time to got back and hide again.}