IPTEL WG                                                     J. Peterson
Internet-Draft                                                   NeuStar
Expires: April 27, 2003                                 October 27, 2002


             The Calling Party's Category tel URL Parameter
                       draft-peterson-tel-cpc-01

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   This Internet-Draft will expire on April 27, 2003.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

Abstract

   This document specifies a new parameter for the tel URL [1] that
   represents the Calling Party's Category, a parameter used in SS7 ISUP
   [2] signaling.












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Table of Contents

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2. Parameter Definition . . . . . . . . . . . . . . . . . . . . . . 3
   3. Usage  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   4. Security Considerations  . . . . . . . . . . . . . . . . . . . . 4
   5. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . . 4
      References . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
      Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
      Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 6









































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1. Introduction

   ISUP defines a Calling Party's Category (CPC) parameter that
   characterizes the station used to originate a call and carries other
   important state that can describe the originating party.  When
   telephone numbers are contained in URLs, such as the tel URL, it may
   be desirable to communicate any CPC associated with that telephone
   number or, in the context of a call, the party calling from it.

   Note that in some networks (including North America), the Originating
   Line Information (OLI) parameter is used to carry this information in
   ISUP rather than the CPC parameter.  Legacy multifrequency (MF)
   signaling networks carry this information in the ANI II Digits.  The
   tel URL parameter specified in this document is designed to carry
   data from these sources as well.

2. Parameter Definition

   The Calling Party's Category is represented as a tel URL parameter.
   The ABNF syntax is as follows:

      cpc                   = cpc-tag "=" cpc-value
      cpc-tag               = "cpc"
      cpc-value             = string

   CPC values (``cpc-value'' strings) must be registered with IANA.  The
   following values are pre-registered by this document:

      ordinary: The caller has been identified, and has no special
      features.

      priority: This call has priority/emergency status.

      data: This call will contain voice-band data.

      test: This is a test call that has been originated as part of a
      maintenance procedure.

      operator: The call was generated by an operator position.

      payphone: The calling station is a payphone.

      prison: The calling station is in a prison.

      unknown: The CPC could not be ascertained.

   An example of the syntax of the CPC parameter (in a small fragment of
   a SIP message) is given below:



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           INVITE sip:bob@biloxi.com SIP/2.0
           To: "Bob" <sip:bob@biloxi.com>
           From: <tel:+17005554141;cpc=payphone>;tag=1928301774


3. Usage

   The CPC is generally useful only when describing the originator of a
   telephone call.  Therefore, when this parameter is used in an
   application such as SIP, it is recommended that the parameter be
   applied to URLs that characterize the originator of a call (such as a
   SIP URI or tel URL in the From header field of a SIP message).

   It is anticipated that this URL will be used primarily by gateways
   that interwork ISUP networks with SIP networks.  Various SIP network
   intermediaries might consult the CPC as they make routing decisions,
   although no specific behavior is prescribed in this document.  While
   no specific mapping of the various ISUP parameters that contain CPC
   data is offered in this document, creating such a mapping would be
   trivial.

   If the CPC parameter is not present, consumers of the CPC should
   treat the URL as if it specified a CPC of "unknown".

   Generally, only one instance of the CPC will be associated with a
   particular URL.

4. Security Considerations

   The information contained in the CPC parameter may be of a private
   nature, and it may not be appropriate for this value to be revealed
   to the destination user (typically it would not be so revealed in the
   PSTN).

   Otherwise, this mechanism adds no new security considerations to
   those discussed in RFC2806 [1].

5. IANA Considerations

   This document requests the creation of an IANA registry for Calling
   Party's Category values.  The values of the CPC parameter in use in
   ISUP are unfortunately quite specific to national networks, and thus
   it is very difficult to uncover all the usages that may be in place
   in various networks.  Note that in North American networks, the
   Originating Line Information parameter contains information common
   found in the Calling Party's Category elsewhere; it is therefore
   legitimate to register values associated with the Originating Line
   Information in this registry.



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   In order to file a registration, interested parties must contact IANA
   and supply them with both a new ``cpc-value'' and a short reason
   phrase describing the usage of the new CPC.  Some values are given in
   Section 2; we ask that these values be pre-registered upon
   publication of this document as an RFC.  It is not expected that this
   registry will require any expert supervision.

References

   [1]  Vaha-Sipila, A., "URLs for Telephone Calls", RFC 2806, April
        2000.

   [2]  International Telecommunications Union, "Recommendation Q.763:
        Signalling System No. 7: ISDN user part formats and codes",
        September 1997, <http://www.itu.int>.

   [3]  Handley, M., Schulzrinne, H., Schooler, E. and J. Rosenberg,
        "SIP: Session Initiation Protocol", RFC 2543, March 1999.


Author's Address

   Jon Peterson
   NeuStar, Inc.
   1800 Sutter St
   Suite 570
   Concord, CA  94520
   US

   Phone: +1 925/363-8720
   EMail: jon.peterson@neustar.biz
   URI:   http://www.neustar.biz/



















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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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