Re: [sipcore] Questions on location conveyance and dereferencing

"Tschofenig, Hannes (NSN - FI/Espoo)" <> Mon, 16 August 2010 06:26 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id AA3473A6819 for <>; Sun, 15 Aug 2010 23:26:29 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -102.496
X-Spam-Status: No, score=-102.496 tagged_above=-999 required=5 tests=[AWL=0.103, BAYES_00=-2.599, USER_IN_WHITELIST=-100]
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id r2C8rfMIhT3b for <>; Sun, 15 Aug 2010 23:26:28 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 37CB53A68B8 for <>; Sun, 15 Aug 2010 23:26:27 -0700 (PDT)
Received: from ([]) by ( with ESMTP id o7G6QwJ2026377 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 16 Aug 2010 08:26:58 +0200
Received: from ( []) by ( with ESMTP id o7G6QvHO000871; Mon, 16 Aug 2010 08:26:58 +0200
Received: from ([]) by with Microsoft SMTPSVC(6.0.3790.4675); Mon, 16 Aug 2010 08:26:57 +0200
X-MimeOLE: Produced By Microsoft Exchange V6.5
Content-class: urn:content-classes:message
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
Date: Mon, 16 Aug 2010 09:26:57 +0300
Message-ID: <>
In-Reply-To: <>
Thread-Topic: [sipcore] Questions on location conveyance and dereferencing
References: <><>, <> <> <>, <> <>, <> <> <> <> <> <>
From: "Tschofenig, Hannes (NSN - FI/Espoo)" <>
To: "ext Elwell, John" <>, "ext Winterbottom, James" <>, <>
X-OriginalArrivalTime: 16 Aug 2010 06:26:57.0743 (UTC) FILETIME=[070DADF0:01CB3D0C]
Subject: Re: [sipcore] Questions on location conveyance and dereferencing
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: SIP Core Working Group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Mon, 16 Aug 2010 06:26:29 -0000

Hi John, 

> > In your enterprise LIS for emergency services you will most 
> > likely want
> > to figure out who is going to consume that reference. Quite 
> likely the
> > PSAP will consume the reference. If so, you better talk to the PSAP
> > responsible for that specific area. 
> [JRE] Quite so, except is it likely my VoIP service provider 
> might also want to inspect the location, to confirm correct 
> routing? Then depending on which SP I choose to route that 
> particular call through, they might support different URI 
> schemes? It seems to be a mess not having a MUST implement scheme.

I understand the theoretical concern. 
I have no objections against a mandatory to implement HTTP-based
dereferencing mechanism. 

> > XMPP does not provide equivalent functionality of SIP location
> > conveyance. 
> > So, another non-issue. 
> [JRE] That was not the point I was making. I was simply 
> saying that even applications that support presence might 
> support XMPP rather than SIMPLE, and therefore would not want 
> to implement RFC 3856. Instead they might prefer to use HTTP.
I am not quite sure which scenario you have in mind. 
If I have an end host that supports XMPP and then gets a location URI
then there is the question of who is going to dereference it. If it is
the end point then it would have to implement the protocol indicated by
the URI scheme. Now, if this happens to be SIP then this end point would
have to implement SIP. The end host could, however, request location by
value instead instead of going through the dance of utilizing a LbyR. 
If the end point does not dereference the LbyR but instead some other
entity then there is the question of how this reference then actually
gets there.