< draft-ietf-ecrit-psap-callback-07.txt   draft-ietf-ecrit-psap-callback-08.txt >
ECRIT H. Schulzrinne ECRIT H. Schulzrinne
Internet-Draft Columbia University Internet-Draft Columbia University
Intended status: Standards Track H. Tschofenig Intended status: Standards Track H. Tschofenig
Expires: June 21, 2013 Nokia Siemens Networks Expires: August 29, 2013 Nokia Siemens Networks
C. Holmberg C. Holmberg
Ericsson Ericsson
M. Patel M. Patel
InterDigital Communications InterDigital Communications
December 18, 2012 February 25, 2013
Public Safety Answering Point (PSAP) Callback Public Safety Answering Point (PSAP) Callback
draft-ietf-ecrit-psap-callback-07.txt draft-ietf-ecrit-psap-callback-08.txt
Abstract Abstract
After an emergency call is completed (either prematurely terminated After an emergency call is completed (either prematurely terminated
by the emergency caller or normally by the call taker) it is possible by the emergency caller or normally by the call taker) it is possible
that the call taker feels the need for further communication. For that the call taker feels the need for further communication. For
example, the call may have been dropped by accident without the call example, the call may have been dropped by accident without the call
taker having sufficient information about the current situation of a taker having sufficient information about the current situation of a
wounded person. A call taker may trigger a callback towards the wounded person. A call taker may trigger a callback towards the
emergency caller using the contact information provided with the emergency caller using the contact information provided with the
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circumstances, be treated like any other call and as a consequence it circumstances, be treated like any other call and as a consequence it
may get blocked by authorization policies or may get forwarded to an may get blocked by authorization policies or may get forwarded to an
answering machine. answering machine.
The IETF emergency services architecture specification already offers The IETF emergency services architecture specification already offers
a solution approach for allowing PSAP callbacks to bypass a solution approach for allowing PSAP callbacks to bypass
authorization policies to reach the caller without unnecessary authorization policies to reach the caller without unnecessary
delays. Unfortunately, the specified mechanism only supports limited delays. Unfortunately, the specified mechanism only supports limited
scenarios. This document discusses shortcomings of the current scenarios. This document discusses shortcomings of the current
mechanisms and illustrates additional scenarios where better-than- mechanisms and illustrates additional scenarios where better-than-
normal call treatment behavior would be desirable. normal call treatment behavior would be desirable. A solution based
on a new header field value, called "psap-callback", for the SIP
Note that this version of the document does not yet specify a Priority header field is specified to accomplish the PSAP callback
solution due to the lack of the working group participants agreeing marking.
on the requirements.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 21, 2013. This Internet-Draft will expire on August 29, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Callback Scenarios . . . . . . . . . . . . . . . . . . . . . . 7 3. Callback Scenarios . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Routing Asymmetry . . . . . . . . . . . . . . . . . . . . 7 3.1. Routing Asymmetry . . . . . . . . . . . . . . . . . . . . 6
3.2. Multi-Stage Routing . . . . . . . . . . . . . . . . . . . 8 3.2. Multi-Stage Routing . . . . . . . . . . . . . . . . . . . 7
3.3. Call Forwarding . . . . . . . . . . . . . . . . . . . . . 9 3.3. Call Forwarding . . . . . . . . . . . . . . . . . . . . . 8
3.4. Network-based Service URN Resolution . . . . . . . . . . . 11 3.4. Network-based Service URN Resolution . . . . . . . . . . . 10
3.5. PSTN Interworking . . . . . . . . . . . . . . . . . . . . 12 3.5. PSTN Interworking . . . . . . . . . . . . . . . . . . . . 11
4. SIP PSAP Callback Indicator . . . . . . . . . . . . . . . . . 13 4. SIP PSAP Callback Indicator . . . . . . . . . . . . . . . . . 12
4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.3. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.3.1. General . . . . . . . . . . . . . . . . . . . . . . . 13 4.3.1. General . . . . . . . . . . . . . . . . . . . . . . . 12
4.3.2. ABNF . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.3.2. ABNF . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5.1. Security Threat . . . . . . . . . . . . . . . . . . . . . 14 5.1. Security Threat . . . . . . . . . . . . . . . . . . . . . 13
5.2. Security Requirements . . . . . . . . . . . . . . . . . . 14 5.2. Security Requirements . . . . . . . . . . . . . . . . . . 13
5.3. Security Solution . . . . . . . . . . . . . . . . . . . . 14 5.3. Security Solution . . . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . . 18 8.1. Normative References . . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
Summoning police, the fire department or an ambulance in emergencies Summoning police, the fire department or an ambulance in emergencies
is one of the fundamental and most-valued functions of the telephone. is one of the fundamental and most-valued functions of the telephone.
As telephone functionality moves from circuit-switched telephony to As telephone functionality moves from circuit-switched telephony to
Internet telephony, its users rightfully expect that this core Internet telephony, its users rightfully expect that this core
functionality will continue to work at least as well as it has for functionality will continue to work at least as well as it has for
the legacy technology. New devices and services are being made the legacy technology. New devices and services are being made
available that could be used to make a request for help, which are available that could be used to make a request for help, which are
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