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Re: [Ecrit] [Fwd: I-D Action:draft-patel-ecrit-sos-parameter-00.txt]
Hi Brian,
I've added comments inline:
I get emergency registration, but perhaps there is a better way to do
it.
I don't get Req 2. No network entity other than the PSAP should be
deleting
the Route entry.
[MILAN] The Route header entry of the PSAP is inserted by the E-CSCF (in
the case of an IP-based PSAP). In the case of a PSTN based PSAP, the
address of the BGCF is added in the Route header, and the PSAP address
is added to the Request URI. Prior to the request reaching the E-CSCF,
the PSAP address is not available in the SIP headers of the INVITE
request.
Req 3 is perverse. The UE is not emergency aware, yet knows about the
URI
parameter. Perhaps you meant that it is emergency aware, but didn't
recognize the dialstring. Redirect the call to urn:service:sos.
[MILAN] UE may be emergency capable, but is emergency unaware since it
doesn't recognize the dialled digits (emergency number plan of the
roamed-to region is not available in the UE) - thus is unaware an
emergency call is dialled. The P-CSCF would then add the appropriate
service URN if network policy is to proceed with the emergency call.
UE recognizes the dialled digits as an emergency call but does not have
an appropriate service URN to add to the Request URI i.e. lifeboat
service. Thus UE adds dialstring to the Request-URI and the network will
add the appropriate service URN (may result in default urn:service:sos
being applied). A backwards indication in these cases would allow the UE
to explicitly be aware that it is involved in an emergency call.
I don't understand Req 4. The gateway has to have some mechanism to
recognize that the call is from the PSAP. It's constructing a From/PAI.
It
can use the correct domain.
[MILAN] In this case, the From/PAI would be a tel-URI. An explicit
marking of the call back aids special handling (network service
suppression).
So, 3GPP needs a way to mark an emergency services registration. It's
possible the URI parameter is the best way to do that. I'll think about
that.
Hmmm. Maybe I'll give you a 5th requirement. An emergency call can be
transferred. The result is an INVITE from the UE with a Referred-by,
which
is the PSAP. The urn:services:sos would not be in the ROUTE header, but
it's still an emergency call. Hmmmm. Lots of PSAPs won't REFER all the
way
back to the caller. They will use some form of B2BUA, but still, the
RIGHT
way to do it is REFER. Hmmmm.
Regards,
Milan
-----Original Message-----
From: ecrit-bounces at ietf.org [mailto:ecrit-bounces at ietf.org] On Behalf
Of Brian Rosen
Sent: 15 September 2008 12:20
To: 'Hannes Tschofenig'; 'ECRIT'
Subject: Re: [Ecrit] [Fwd: I-D
Action:draft-patel-ecrit-sos-parameter-00.txt]
I get emergency registration, but perhaps there is a better way to do
it.
I don't get Req 2. No network entity other than the PSAP should be
deleting
the Route entry.
Req 3 is perverse. The UE is not emergency aware, yet knows about the
URI
parameter. Perhaps you meant that it is emergency aware, but didn't
recognize the dialstring. Redirect the call to urn:service:sos.
I don't understand Req 4. The gateway has to have some mechanism to
recognize that the call is from the PSAP. It's constructing a From/PAI.
It
can use the correct domain.
So, 3GPP needs a way to mark an emergency services registration. It's
possible the URI parameter is the best way to do that. I'll think about
that.
Hmmm. Maybe I'll give you a 5th requirement. An emergency call can be
transferred. The result is an INVITE from the UE with a Referred-by,
which
is the PSAP. The urn:services:sos would not be in the ROUTE header, but
it's still an emergency call. Hmmmm. Lots of PSAPs won't REFER all the
way
back to the caller. They will use some form of B2BUA, but still, the
RIGHT
way to do it is REFER. Hmmmm.
Brian
> -----Original Message-----
> From: ecrit-bounces at ietf.org [mailto:ecrit-bounces at ietf.org] On Behalf
Of
> Hannes Tschofenig
> Sent: Monday, September 15, 2008 3:24 AM
> To: 'ECRIT'
> Subject: [Ecrit] [Fwd: I-D
Action:draft-patel-ecrit-sos-parameter-00.txt]
>
> Please take a look at this document. Milan would like to hear some
> comments!
>
> Ciao
> Hannes
>
> -------- Original Message --------
> Subject: I-D Action:draft-patel-ecrit-sos-parameter-00.txt
> Date: Fri, 12 Sep 2008 09:45:01 -0700 (PDT)
> From: Internet-Drafts at ietf.org
> Reply-To: internet-drafts at ietf.org
> To: i-d-announce at ietf.org
>
>
>
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories.
>
> Title : SOS Uniform Resource Identifier (URI)
parameter
> for marking of Session Initiation Protocol (SIP) requests related to
> emergency services
> Author(s) : M. Patel
> Filename : draft-patel-ecrit-sos-parameter-00.txt
> Pages : 9
> Date : 2008-09-12
>
> This memo describes requirements and protocol conventions for a new
> SIP (Session Initiation Protocol) URI parameter intended for marking
> SIP requests and responses related to emergency services. This
> proposal addresses issues that exist in the current 3rd Generation
> Partnership Project IP Multimedia Subsystem (IMS) Emergency services
> solution, but is not precluded from being used by other SIP-based
> emergency services solutions. It is not intended as a replacement
> for the service URN.
>
> A URL for this Internet-Draft is:
>
http://www.ietf.org/internet-drafts/draft-patel-ecrit-sos-parameter-00.t
xt
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> Below is the data which will enable a MIME compliant mail reader
> implementation to automatically retrieve the ASCII version of the
> Internet-Draft.
>
>
> _______________________________________________
> Ecrit mailing list
> Ecrit at ietf.org
> https://www.ietf.org/mailman/listinfo/ecrit
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