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rfc:rfc5341

Network Working Group C. Jennings Request for Comments: 5341 Cisco Systems Updates: 3966 V. Gurbani Category: Standards Track Bell Laboratories, Alcatel-Lucent

                                                        September 2008
           The Internet Assigned Number Authority (IANA)
      tel Uniform Resource Identifier (URI) Parameter Registry

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.

Abstract

 This document creates an Internet Assigned Number Authority (IANA)
 registry for tel Uniform Resource Identifier (URI) parameters and
 their values.  It populates the registry with the parameters defined
 in the tel URI specification, along with the parameters in tel URI
 extensions defined for number portability and trunk groups.

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
 2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 2
 3.  Use of the Registry . . . . . . . . . . . . . . . . . . . . . . 2
 4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
   4.1.  tel URI Parameters Registry . . . . . . . . . . . . . . . . 3
   4.2.  Registration Policy for tel URI Parameters  . . . . . . . . 4
 5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
 6.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
   7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
   7.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

Jennings & Gurbani Standards Track [Page 1] RFC 5341 IANA Registry for TEL URI Parameters September 2008

1. Introduction

 The tel URI (RFC 3966 [1]), defines a URI that can be used to
 represent resources identified by telephone numbers.  The tel URI,
 like many other URIs, provides extensibility through the definition
 of new URI parameters and new values for existing parameters.
 However, RFC 3966 did not specify an IANA registry where such
 parameters and values can be listed and standardized.  This
 specification creates such a registry.

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 [2].

3. Use of the Registry

 The tel URI parameters and values for these parameters MUST be
 documented in a RFC or other permanent and readily available public
 specification in order to be registered by IANA.  This documentation
 MUST fully explain the syntax, intended usage, and semantics of the
 parameter.  The intent of this requirement is to assure
 interoperability between independent implementations, and to prevent
 accidental namespace collisions between implementations of dissimilar
 features.
 Documents defining tel URI parameters or parameter values MUST
 register them with IANA, as described in Section 4.  The IANA
 registration policy for such parameters is "Specification Required,
 Designated Expert," and is further discussed in Section 4.2.
 Some tel URI parameters only accept a set of predefined parameter
 values while others can take any value.  There are also parameters
 that do not have any value; they are used as flags.
 Those URI parameters that take on predefined values typically take on
 a large number of values.  Registering each of those values, or
 creating a sub-registry for each such parameter is not appropriate.
 Instead, we have chosen to register URI parameter values by
 reference.  That is, the entry in the URI parameter registry for a
 given URI parameter contains references to the RFCs defining new
 values of that parameter.
 Accordingly, the tel URI parameter registry contains a column that
 indicates whether or not each parameter accepts a value.  The column
 may contain "No value" or "Constrained".  A "Constrained" in the
 column implies that certain predefined values exist for this

Jennings & Gurbani Standards Track [Page 2] RFC 5341 IANA Registry for TEL URI Parameters September 2008

 parameter and the accompanying RFC or other permanent and readily
 available public specification should be consulted to find out the
 accepted set of values.  A "No Value" in the column implies that the
 parameter is used either as a flag, or does not have a set of
 predefined values.  The accompanying RFC or other permanent and
 readily available public specification should provide more
 information on the semantics of the parameter.

4. IANA Considerations

 The specification creates a new IANA registry named "tel URI
 Parameters".

4.1. tel URI Parameters Registry

 New tel URI parameters and new values for existing tel URI parameters
 MUST be registered with IANA.
 When registering a new tel URI parameter, the following information
 MUST be provided:
 o  Name of the parameter.
 o  Whether the parameter only accepts a set of predefined values.
 o  Reference to the RFC or other permanent and readily available
    public specification defining the parameter and new values.
 When registering a new value for an existing tel URI parameter, the
 following information MUST be provided:
 o  Name of the parameter.
 o  Reference to the RFC or other permanent and readily available
    public specification providing the new value.
 Table 1 contains the initial values for this registry.

Jennings & Gurbani Standards Track [Page 3] RFC 5341 IANA Registry for TEL URI Parameters September 2008

 Parameter Name     Predefined Values     Reference
 --------------     -----------------     ---------
 isub               Constrained           [RFC3966]
 isub-encoding      Constrained           [RFC4715]
 ext                Constrained           [RFC3966]
 phone-context      Constrained           [RFC3966]
 enumdi             No value              [RFC4759]
 npdi               No value              [RFC4694]
 rn                 Constrained           [RFC4694]
 rn-context         Constrained           [RFC4694]
 cic                Constrained           [RFC4694]
 cic-context        Constrained           [RFC4694]
 tgrp               Constrained           [RFC4904]
 trunk-context      Constrained           [RFC4904]
 Table 1: IANA tel URI parameter registry

4.2. Registration Policy for tel URI Parameters

 As per the terminology in [3] and actions accorded to such a role,
 the registration policy for tel URI parameters shall be
 "Specification Required, Designated Expert" (the former implicitly
 implies the latter).
 The Designated Expert, when deliberating on whether to include a new
 parameter in the tel URI registry, may use the criteria provided
 below to reach a decision (this is not an exhaustive list but
 representative of the issues to consider when rendering an equitable
 decision):
 o  If the tel URI -- with the parameter under consideration -- will
    be converted to a URI used by other signaling protocols such as
    the Session Initiation Protocol (SIP [5]) or H.323 [7], then the
    expert must consider whether this parameter merely encapsulates
    signaling information that is not meaningful to the processing of
    requests in the domain of the converted URI.  For example, certain
    Integrated Services Digital Network (ISDN) User Part (ISUP, [8])
    parameters have no equivalent corollary in SIP; thus, their
    presence or absence in a SIP URI will not hinder the normal rules
    for processing that URI.  Other parameters may affect the normal
    processing rules associated with the URI; in such cases, the
    expert must carefully consider the ramifications, if any, of the
    presence of such parameters.
 o  Certain parameters of a tel URI can be optional.  These parameters
    act as metadata about the identifier in the tel URI.  Optional
    parameters should provide additional information to a service for
    which they apply instead of acting as enablers of that service in

Jennings & Gurbani Standards Track [Page 4] RFC 5341 IANA Registry for TEL URI Parameters September 2008

    the first place.  The service must continue to be invoked and
    operate normally even in the absence of these parameters.

5. Security Considerations

 The registry in this document does not in itself have security
 considerations.  However, as mentioned in [4], an important reason
 for the IETF to manage the extensions of SIP is to ensure that all
 extensions and parameters are able to provide secure usage.  The
 supporting RFC publications for parameter registrations described in
 this specification MUST provide detailed security considerations for
 them.

6. Acknowledgments

 The structure of this document comes from [6], which is the
 equivalent work done in the SIP domain to establish a registry.  Ted
 Hardie, Alfred Hoenes, Jon Peterson, and Jonathan Rosenberg provided
 substantive comments that have improved this document.
 Brian Carpenter, Lars Eggert, Pasi Eronen, Chris Newman, and Glen
 Zorn provided feedback during IESG review and Gen-ART review.

7. References

7.1. Normative References

 [1]  Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966,
      December 2004.
 [2]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.
 [3]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
      Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.

7.2. Informative References

 [4]  Mankin, A., Bradner, S., Mahy, R., Willis, D., Ott, J., and B.
      Rosen, "Change Process for the Session Initiation Protocol
      (SIP)", BCP 67, RFC 3427, December 2002.
 [5]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
      Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
      Session Initiation Protocol", RFC 3261, June 2002.

Jennings & Gurbani Standards Track [Page 5] RFC 5341 IANA Registry for TEL URI Parameters September 2008

 [6]  Camarillo, G., "The Internet Assigned Number Authority (IANA)
      Uniform Resource Identifier (URI) Parameter Registry for the
      Session Initiation Protocol (SIP)", BCP 99, RFC 3969,
      December 2004.
 [7]  ITU-T H.323, "H.323: Packet-based multimedia communications
      systems", June 2006.
 [8]  ITU-T Q.764, "Signaling System No. 7: ISDN User Part Signaling
      Procedures", December 1999.

Authors' Addresses

 Cullen Jennings
 Cisco Systems
 170 West Tasman Drive
 Mailstop SJC-21/2
 San Jose, CA  95134
 USA
 Phone:  +1 408 902-3341
 EMail:  fluffy@cisco.com
 Vijay K. Gurbani
 Bell Laboratories, Alcatel-Lucent
 2701 Lucent Lane
 Room 9F-546
 Lisle, IL  60532
 USA
 Phone:  +1 630 224-0216
 EMail:  vkg@alcatel-lucent.com

Jennings & Gurbani Standards Track [Page 6] RFC 5341 IANA Registry for TEL URI Parameters September 2008

Full Copyright Statement

 Copyright (C) The IETF Trust (2008).
 This document is subject to the rights, licenses and restrictions
 contained in BCP 78, and except as set forth therein, the authors
 retain all their rights.
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 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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Jennings & Gurbani Standards Track [Page 7]

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