Subject: [Ecrit] PSAP Callback -- Questions I distributed

From: Hannes Tschofenig <[email-masked]>
Date: Wed, 03 Mar 2010 21:11:02 +0200

I thought I had forwarded my mail to the ECRIT list but obviously I 
failed todo so. Here is the text I sent to NENA, EENA, and ETSI EMTEL.
My hope is to have some initial feedback for discussion at the next IETF 
meeting. I got some responses already. So, things are looking good and I 
am sending out messages to individual people from emergency services 
organizations as well.

Ciao
Hannes

-------------------

Hi all,

To progress the work on PSAP callback in the IETF ECRIT group we are 
soliciting feedback from this group.

A little bit of background first:  When you make an IP-based emergency 
call to an IP-based PSAP then the PSAP will get two pieces of identity 
information about the emergency caller:

  * Contact-URI: Information that uniquely identifies the device the 
call came from.
  * Address of Record: Long-term contact information

Imagine that the communication between the PSAP and the emergency caller 
gets interrupted prematurely and the PSAP wants to call back to the 
emergency caller, for example to obtain more information about the 
incident.

The idea of the ongoing PSAP callback work is to allow the emergency 
call to override any call forwarding Procedures configured by the 
emergency caller's phone, do not disturb functionality, etc. so that the 
call indeed reaches the emergency caller. This includes the ability to 
disable network based services, such as network based call forwarding, 
in addition to functionality configured at the phone itself.

1st question: What functionality is available in today's CS networks?

2nd question: Is this useful functionality to have for IP-based 
emergency services?

3rd question: Do you envision a time-restriction on this capability? 
Example: only within one hour callbacks from the PSAP are treated 
differently to normal calls.

4th question: Would you expect the call to reach primarily the device 
that initiated the emergency call?
  
5th question: In some cases the device that was used to originally 
initiate the call does not respond anymore to a callback (e.g. imagine a 
fixed line phone that was used to report a fire in a house and is out of 
order soon afterwards). Since the initial emergency call provided a 
second contact mechanism (namely the address of record) it could be used 
by the call taker as well. Should this communication also experience the 
same type of override privilege as the initially transmitted callback to 
the emergency caller's device? 

Thank you for your time. Your feedback is very valuable to us.

Ciao
Hannes

---

From: Gunnar Hellström <[email-masked]>
Date: Wed, 3 Mar 2010 20:43:18 +0100

Hannes,
You say:
"The idea of the ongoing PSAP callback work is to allow the emergency call
to override any call forwarding Procedures configured by the emergency
caller's phone, do not disturb functionality, etc. so that the call indeed
reaches the emergency caller. This includes the ability to disable network
based services, such as network based call forwarding, in addition to
functionality configured at the phone itself."

I have warned a number of times that this functionality sound contra
productive against the mechanisms in use or planned for automatic relay
service invocation. There may be very important network based call
forwarding, or phone configured call forwarding functions involved in making
the call reach both the user and a suitable coaching service (e.g. relay
service ). If these functions are put out of operation when the PSAP calls
back, you will end up with a call taker and a user with a connected call,
but without a chance to understand each other.

I think we need to create a coaching service invocation draft in parallel
with the callback drafting, and verify that the callback requirements you
talk about do not destroy the opportunities to get coaching services invoked
in callback calls.

Gunnar 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Hannes Tschofenig
Sent: Wednesday, March 03, 2010 8:11 PM
To: 'ECRIT'
Subject: [Ecrit] PSAP Callback -- Questions I distributed

Ciao
Hannes

-------------------

Hi all,

  

Ciao
Hannes

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---

From: Brian Rosen <[email-masked]>
Date: Wed, 03 Mar 2010 14:54:53 -0500

In the U.S., this works, except in a very small percentage of cases where
call forwarding is a permanent feature, and there is often no actual service
behind it (that is, no wire, no service, no device).  You would call forward
in all circumstances.

We implement the coaching (relay) service with normal PSTN routing, and not
call forwarding.

Brian

---

From: Gunnar Hellström <[email-masked]>
Date: Thu, 4 Mar 2010 11:44:52 +0100

The mechanism for callback including coaching services must still work, even
when the PSAP calls back with multimedia, and when "normal PSTN routing" is
not involved.

We need to verify both that the information provided with the incoming call
is sufficient for the call back.
Hannes says:
">   * Contact-URI: Information that uniquely identifies the device the
>   * Address of Record: Long-term contact information
"
Can these contain URI-lists, if that is selected to be the way a coaching
service and the calling user are supposed to be connected?

Or are they single addresses resolved to multi-party calls by network
elements.

Do we need to add also a record of offered media or agreed media during the
incoming call, and use the same set for the callback? 
Or will the PSAP always make the callback out with full Total Conversation
media offer (video, real-time text and audio) and accept to have the call in
the agreed subset of media?

Gunnar

-----Original Message-----
From: Brian Rosen [mailto:[email-masked]] 
Sent: Wednesday, March 03, 2010 8:55 PM
To: Gunnar Hellström; 'Hannes Tschofenig'; 'ECRIT'
Subject: Re: [Ecrit] PSAP Callback -- Questions I distributed

Brian

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