The ENUM Dip Indicator Parameter for the "tel" URI
RFC 4759

 
Document Type RFC - Proposed Standard (December 2006; No errata)
Last updated 2013-03-02
Stream IETF
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IESG IESG state RFC 4759 (Proposed Standard)
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Responsible AD Cullen Jennings
Send notices to jdrosen@cisco.com, fluffy@cisco.com
Network Working Group                                         R. Stastny
Request for Comments: 4759                                         Oefeg
Category: Standards Track                                     R. Shockey
                                                            Neustar Inc.
                                                               L. Conroy
                                                     Roke Manor Research
                                                           November 2006

           The ENUM Dip Indicator Parameter for the "tel" URI

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The IETF Trust (2006).

Abstract

   This document defines a new parameter "enumdi" for the "tel" Uniform
   Resource Identifier (URI) to support the handling of ENUM queries in
   Voice over Internet Protocol (VoIP) network elements.  A VoIP network
   element may receive a URI containing an E.164 number, where that URI
   contains an "enumdi" parameter.  The presence of the "enumdi"
   parameter indicates that an ENUM query has already been performed on
   the E.164 number by a previous VoIP network element.  Equally, if a
   VoIP network element sends such a URI, it asserts that an ENUM query
   has been carried out on this number.

Stastny, et al.             Standards Track                     [Page 1]
RFC 4759         ENUM Dip Indicator "tel" URI parameter    November 2006

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................2
   3. Formal Syntax ...................................................3
   4. Normative Rules .................................................3
      4.1. Options for ENUM Domain Providers ..........................3
      4.2. Client Behaviour for VoIP Network Elements .................3
           4.2.1. Handling a URI with the "enumdi" Parameter ..........3
           4.2.2. Adding the "enumdi" Parameter to URIs ...............4
           4.2.3. Handling a URI Retrieved from ENUM ..................4
   5. Examples ........................................................4
   6. Security Considerations .........................................5
   7. IANA Considerations .............................................5
   8. Acknowledgements ................................................6
   9. References ......................................................6
      9.1. Normative References .......................................6
      9.2. Informative References .....................................6

1.  Introduction

   VoIP network elements (including User Agent Servers and User Agent
   Clients) may be set up in different ways to handle E.164 [3] numbers
   during call setup, depending on the capabilities provided.  One
   common approach is to query ENUM as defined in RFC 3761 [4], and to
   use the set of NAPTR resource records that is returned.

   If the ENUM query leads to a result, the call is set up accordingly.
   If the ENUM query does not lead finally to a result, another database
   may be queried and/or the call may finally be routed to the Public
   Switched Telephone Network (PSTN).  In doing so, the call may be
   routed to another VoIP network element.  To indicate in signalling to
   this next VoIP element that an ENUM query has already been made for
   the "tel" URI (specified in RFC 3966 [5]), the "enumdi" parameter is
   used, to prevent the next VoIP network element from repeating
   redundant queries.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
   NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
   this document are to be interpreted as described in BCP 14, RFC 2119
   [1].

Stastny, et al.             Standards Track                     [Page 2]
RFC 4759         ENUM Dip Indicator "tel" URI parameter    November 2006

3.  Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) as described in RFC 4234 [2] to extend the syntax of the
   "par" production defined in the ABNF of RFC 3966 [5].
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