VPIM Working Group                                        Glenn Parsons
Internet Draft                                          Janusz Maruszak
Document: <draft-ema-vpim-clid-04.txt>                  Nortel Networks
Category: Standards Track                                    April 2002


          Calling Line Identification for Voice Mail Messages


Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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Abstract

   This document describes a method for identifying the originating
   calling party in the headers of a stored voice mail message.




























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Table of Contents


 1. Abstract........................................................3
 2. Conventions used in this document...............................3
 3. Introduction....................................................3
 4. Calling Line Identification Field...............................4
    4.1 Internal Call...............................................4
    4.2 External Call...............................................4
 5. Caller Name Field...............................................5
 6. Formal Syntax...................................................5
    6.1 Calling Line Identification Syntax..........................6
    6.2 Caller Name Syntax..........................................6
    6.3 Example.....................................................6
 7. Security Considerations.........................................6
 8. References......................................................6
 9. Acknowledgments.................................................8
 10. Author's Addresses.............................................8
 11. Full Copyright Statement.......................................9






































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1. Abstract

   This document describes a method for identifying the originating
   calling party in the headers of a stored voice mail message.


2. Conventions used in this document

   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 RFC-2119.


3. Introduction

   There is currently a need for a mechanism to identify the
   originating party of a voice mail message, outside of the "FROM"
   header information.  The telephone number and name of the caller are
   typically available from the telephone network, but there is no
   obvious header field to store this in an Internet Mail message.

   This information is intended for use when the VPIM message format is
   used for storing "Call Answer" voice messages in an Internet Mail
   message store, i.e. the calling party leaves a voice message for the
   recipient, who was unable to answer the call.

   [VPIMV2R2] suggests the originating number be included as an
   Internet address, using the first method shown below. There are
   several other ways to store this information, but they all involve
   some manipulation of the "From" field.  For example:

      1. From: "416 555 1234" <non-mail-user@host>
      2. From: "John Doe" <4165551234@host>
      3. From:  unknown:;

   As a result, it is useful to be able to store the calling party's
   name and number as presented to the called party without
   manipulation.  This would allow future generation of the proper
   Internet address, and also display of this information to the
   recipient.  Note that there is no requirement to store meta-data
   (e.g., type of number, presentation restricted) as this information
   is not presented to the called party and is generally not available
   to voice mail systems.  The intent is to store the information
   available to an analog (non-ISDN) phone (e.g., per [T1.401] in North
   America).

   [RFC2076] currently lists "phone" as an Internet message header
   which would hold the originating party's telephone number, but it is
   listed as "non-standard", i.e. usage of this header is not generally
   recommended. It also has no defined format, making the information
   unparsable. There is no similar entry for the originator's name.

   It is proposed that two new message header fields be included to
   hold this information, namely the Calling Line Identification
   ("Caller-ID"), and Caller Name ("Caller-Name").




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4. Calling Line Identification Field

   The Calling Line Identification header ("Caller-ID") is to hold
   sufficient information for the recipient to call back, or reply to,
   the sender of the message.  This leads to two distinct
   possibilities: internal and external calling.

   Note that for both possibilities, the number field MUST contain only
   the digits of the number and MUST be representable using the
   American Standard Code for Information Interchange [ASCII] character
   set; it does not include any separating character (e.g. "-").

   It is expected that default, and likely most common case, will not
   have any numbering plan semantic associated with the number.
   However, in the case that it is known, an optional "NumberingPlan"
   parameter MAY be used to indicate the semantic.


4.1 Internal Call

   For an internal call (e.g. between two extensions within the same
   company), it is sufficient to relay only the extension of the
   calling party, based on the company dialing plan.


4.2 External Call

   For an international call, the calling partyÆs number must be the
   full international number as described in [E.164], i.e. Country Code
   (CC), National Destination Code (NDC) and Subscriber Number (SN).
   Other information, such as prefixes or symbols (e.g. "+"), MUST NOT
   be included.  This requires provisioning for up to 15 digits.

   For a call within North America, it is also suggested to support 15
   digits per [T1.625].  However, some service providers may only
   support 10 digits as described in [T1.401] and [GR-31-CORE].  Though
   it is desirable that an international number NOT be truncated to 10
   digits if it contains more, it is recognized that this will happen
   due to limitations of various systems.

   Also note that the date and time can be included with the calling
   partyÆs telephone number per [T1.401].  This MAY be used, as there
   is an existing "Date" Internet header to hold this information.  It
   is a local implementation decision whether this time or the local
   system time be recorded in the "Date" header.

   Note that the other defined fields available to non-analog systems
   (e.g., subaddress, redirecting number), as well as the meta-data,
   are not intended to be stored in this header.


4.3 Numbering Plan

   In this baseline case (i.e., analog lines), no numbering plan
   information is known or implied.  However, in the case that a
   numbering plan is known, an optional "NumberingPlan" parameter MAY

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   be used to indicate the semantic.  Only two semantics are defined û
   "local" and "e164".  "local" is the default if no numbering plan
   semantic is included.  Further, "local" has meaning only within the
   FQDN of the sending system identified in the RFC 2822 "From" field.
   "e164".  "e164" indicates that the number is as described in
   [E.164]. "x-" may be used to indicate vendor specific dialing plans.


5. Caller Name Field

   The name of the person sending the message is also important.  If
   available, it is to be included whether the call is internal or
   external.  This field may not be available on an international call.

   Further, the exact format for this field is typically a service
   provider option per [T1.641].  It is possible for the callerÆs name
   to be sent in one of several character sets depending on the service
   provider signaling transport (e.g., ISDN-UP, SCCP, TCAP).  These
   include:
      1) International Reference Alphabet (IRA), formerly know as
        International Alphabet No.5 or IA5 [T.50]
      2) Latin Alphabet No. 1 [8859-1]
      3) American National Standard Code for Information Interchange
        [ASCII]
      4) Character Sets for the International Teletex Service [T.61]

   Of these, the IRA and T.61 character set contains a number of
   options that help specify national and application oriented
   versions.  If there is no agreement between parties to use these
   options, then the 7-bit character set in which the graphical
   characters of IRA, T.61 and ASCII are coded exactly the same, will
   be assumed.  Further, the 7-bit graphical characters of [8859-1] are
   the same as in [ASCII].

   Note that for delivery to customer equipment in North America, the
   calling name MUST be presented in ASCII per [T1.401].

   As a result, for the caller name header defined in this document,
   characters are represented with ASCII characters.  However, if a
   name is received that cannot be represented in 7-bit ASCII, it may
   be stored using its native character set as defined in [RFC2047].

   In the networks, the length of the name field MUST NOT exceed 50
   characters, as defined in [T1.641].  However, service providers may
   chose to limit this further to 15 characters for delivery to
   customer equipment, e.g., [T1.401] and [GR-1188-CORE].


6. Formal Syntax

   Both Calling Line Identification and Caller Line follow the syntax
   specification using the augmented Backus-Naur Form (BNF) as
   described in [RFC2234].  While the semantics of these headers are
   defined in sections 4 and 5, the syntax uses the æunstructuredÆ
   token defined in [RFC2822]:

      unstructured = *([FWS] utext) [FWS]


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6.1 Calling Line Identification Syntax

      "Caller-ID" ":" 1*DIGIT [ "," "NumberingPlan="
      ( "local" / "e164" / ietf-token / x-token ) ] CRLF

        ietf-token := <An extension token defined by a
                       standards-track RFC and registered
                       with IANA.>

        x-token := <The two characters "X-" or "x-" followed, with
                    no intervening white space, by any token>


6.2 Caller Name Syntax

      "Caller-Name" ":" unstructured CRLF


6.3 Example

       To: +19725551212@vm1.mycompany.com
       Caller-ID: 6137684087
       Caller-Name: Derrick Dunne


7. Security Considerations

   There are a few scenarios that must be considered.  The first is
   mentioned in section 2.2 - the truncation of an international number
   to 10 digits.  This could result in a misinterpretation of the
   resulting number.  For instance, an international number (e.g. from
   Ireland) of the form "353 91 73 3307" could be truncated to "53 91
   73 3307" if received in North America, and interpreted as "539 112
   3456" - a seemingly "North American" style number.  Thus leaving the
   recipient with the incorrect information to reply to the message û
   and possibly with an annoyed callee at the North American number.

   The second scenario is the possibility of sending an internal
   extension to an external recipient when a Call Answer message is
   forwarded.  This poses two problems, the recipient is given the
   wrong phone number, and the company's dialing plan could be exposed.

   The final concern deals with exercising character options that are
   available in coding the Calling Name field. An international system
   may send a message with coding options that are not available on the
   receiving system. Thus giving the recipient an incorrect Caller
   Name.

   Note that unlisted and restricted numbers are not a concern as these
   header fields are defined to contain what the called party would see
   (e.g., 'Private Name'), as opposed to the complete details exchanged
   between service providers.


8. References



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   [VPIMV2R2] Vaudreuil, Greg, Parsons, Glenn, "Voice Profile for
   Internet Mail, version 2", <draft-ietf-vpim-vpimv2r2-03.txt>, June
   2001.

   [RFC2047] K. Moore, "MIME (Multipurpose Internet Mail Extensions)
   Part Three:  Message Header Extensions for Non-ASCII Text", RFC 2047,
   November 1996

   [RFC2076] Palme, "Common Internet Message Headers", RFC 2076,
   February 1997

   [RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
   Syntax Specifications: ABNF", RFC 2234, Internet Mail Consortium and
   Demon Internet Ltd., November 1997

   [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April
   2001.

   [E.164] ITU-T Recommendation E.164 (1997), "The international public
   telecommunication numbering plan"

   [T.50] ITU-T Recommendation T.50 (1992), "International Reference
   Alphabet (IRA)"

   [T.61] CCITT Recommendation T.61 (1988) (Withdrawn), "Character
   Repertoire and Coded Chaacter Sets for the International Teletex
   Service"

   [8859-1] ISO/IEC International Standard 8859-1 (1998), Information
   Technology û 8-bit single-byte coded graphic character sets û Part 1:
   Latin Alphabet No. 1

   [ASCII] American National Standards Institute (ANSI), Coded
   Character Set - 7-Bit American National Standard Code for
   Information Interchange, ANSI X3.4, 1986.

   [T1.401] American National Standards Institute (ANSI),
   Telecommunications û Network-to-Customer Installation Interfaces û
   Analog Voicegrade Switched Access Lines with Calling Number
   Delivery, Calling Name Delivery, or Visual Message-Waiting Indicator
   Features, ANSI T1.6401.03-1998

   [T1.625] American National Standards Institute (ANSI),
   Telecommunications - Integrated Services Digital Network (ISDN) û
   Calling Line identification Presentation and Restriction
   Supplementary Services, ANSI T1.625-1993

   [T1.641] American National Standards Institute (ANSI),
   Telecommunications - Calling Name Identification Presentation, ANSI
   T1.641-1995

   [GR-1188-CORE] Telcordia Technologies, "CLASS Feature: Calling Name
   Delivery Generic Requirements", GR-1188-CORE, Issue 2, December 2000

   [GR-31-CORE] Telcordia Technologies, "CLASS Feature: Calling Number
   Delivery", GR-31-CORE, Issue 1, June 2000



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9. Acknowledgments

   The previous authors of drafts of this document were Derrick Dunne
   and Jason Collins. The current authors would like to thank Derrick
   and Jason for their contributions.


10. Author's Addresses

   Glenn Parsons
   Nortel Networks
   P.O. Box 3511, Station C
   Ottawa, ON K1Y 4H7
   Phone: +1-613-763-7582
   Email: gparsons@nortelnetworks.com

   Janusz Maruszak
   Nortel Networks
   522 University Avenue
   Toronto, ON M5G 1W7
   Phone: +1-416-597-7517
   Email: marusj@nortelnetworks.com





































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11. Full Copyright Statement

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

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   The limited permissions granted above are perpetual and will not be
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   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
































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