Best Current Practice for Communications Services in Support of Emergency Calling
RFC 6881

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Internet Engineering Task Force (IETF)                          B. Rosen
Request for Comments: 6881                                       NeuStar
BCP: 181                                                         J. Polk
Category: Best Current Practice                            Cisco Systems
ISSN: 2070-1721                                               March 2013

          Best Current Practice for Communications Services in
                      Support of Emergency Calling

Abstract

   The IETF and other standards organizations have efforts targeted at
   standardizing various aspects of placing emergency calls on IP
   networks.  This memo describes best current practice on how devices,
   networks, and services using IETF protocols should use such standards
   to make emergency calls.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   BCPs is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6881.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Rosen & Polk              Best Current Practice                 [Page 1]
RFC 6881                Emergency Call Phone BCP              March 2013

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Overview of How Emergency Calls Are Placed ......................3
   4. Which Devices and Services Should Support Emergency Calls? ......4
   5. Identifying an Emergency Call ...................................4
   6. Location and Its Role in an Emergency Call ......................5
      6.1. Types of Location Information ..............................6
      6.2. Location Determination .....................................6
           6.2.1. User-Entered Location Information ...................6
           6.2.2. Access Network "Wire Database" Location
                  Information .........................................6
           6.2.3. End System Measured Location Information ............7
           6.2.4. Network Measured Location Information ...............7
      6.3. Who Adds Location?  The Endpoint, or the Proxy? ............8
      6.4. Location and References to Location ........................8
      6.5. End System Location Configuration ..........................8
      6.6. When Location Should Be Configured ........................10
      6.7. Conveying Location ........................................11
      6.8. Location Updates ..........................................11
      6.9. Multiple Locations ........................................12
      6.10. Location Validation ......................................12
      6.11. Default Location .........................................13
      6.12. Other Location Considerations ............................13
   7. LIS and LoST Discovery .........................................13
   8. Routing the Call to the PSAP ...................................14
   9. Signaling of Emergency Calls ...................................15
      9.1. Use of TLS ................................................15
      9.2. SIP Signaling Requirements for User Agents ................16
      9.3. SIP Signaling Requirements for Proxy Servers ..............17
   10. Callbacks .....................................................18
   11. Mid-Call Behavior .............................................19
   12. Call Termination ..............................................19
   13. Disabling of Features .........................................19
   14. Media .........................................................20
   15. Testing .......................................................21
   16. Security Considerations .......................................22
   17. IANA Considerations ...........................................22
      17.1. Test Service URN .........................................22