VPIM Working Group                                        Jason Collins
Internet Draft                                          Nortel Networks
Document: <draft-ema-vpim-clid-01.txt>                    November 2000
Category: Standards Track


             Calling Line Identification for VPIM 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
   Task Force (IETF), its areas, and its working groups. Note that
   other groups may also distribute working documents as Internet-
   Drafts. Internet-Drafts are draft documents valid for a maximum of
   six months and may be updated, replaced, or obsoleted by other
   documents at any time. It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."
   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt
   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.



































Collins                   Expires: 24/05/01                          1
                     Calling Line Identification         November 2000




Table of Contents


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




. Abstract

   This document describes a method for identifying the originating
   calling party for a stored VPIM message.


. 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.


. Introduction

   There is currently a need for a mechanism to identify the
   originating party of a VPIM 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 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>

Collins                   Expires: 24/05/01                          2
                     Calling Line Identification         November 2000


      3. From:  unknown:;

   As a result, it is useful to be able to store the calling party's
   name and number as-is without manipulation.  This would allow future
   generation of the proper Internet address, and also display of this
   information to the recipient.

   [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 in
   general 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").


. 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, this 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. "-").


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 CLID 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 sufficient to only include 10
   digits as described in [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 [GR-31-Core] also specifies how to include the date
   and time with the originating telephone number. This MAY be
   followed, as there is an existing "Date" Internet header intended to
   hold this information.  It is a local implementation decision


Collins                   Expires: 24/05/01                          3
                     Calling Line Identification         November 2000


   whether this time or the local system time be recorded in the "Date"
   header.


. 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.  The name MUST be representable using the International
   Reference Alphabet (IRA), formerly know as International Alphabet
   No.5 or IA5.   This is the character set used to transmit the caller
   name in the PSTN.

   The IRA 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 default character set
   "International Reference Version (IRV)" will be chosen. The
   graphical characters of IRV and ASCII are coded exactly the same.
   As a result, for the caller name header defined in this document,
   characters are represented with ASCII characters.

   The length of the name field MUST NOT exceed 15 characters, as
   defined in [GR-1188-CORE].  It MAY contain punctuation or white
   spaces as appropriate.


. Formal Syntax

   Both Calling Line Identification and Caller Line follow the syntax
   specification using the augmented Backus-Naur Form (BNF) as
   described in [RFC2234].

6.1 Calling Line Identification Syntax

      "Caller-ID" ":" 1*15DIGIT CRLF

6.2 Caller Name Syntax

      "Caller-Name" ":" 1*15CHAR CRLF

6.3 Example

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


. 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.


Collins                   Expires: 24/05/01                          4
                     Calling Line Identification         November 2000


   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.


. References

   [VPIMV2R2] Vaudreuil, Greg, Parsons, Glenn, "Voice Profile for
   Internet Mail, version 2", <draft-ietf-vpim-vpimv2r2-01.txt>,
   November 2000.

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

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

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

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

   [GR-1188-CORE] Telecordia Technologies, "CLASS Feature: Calling Name
   Delivery Generic Requirements", GR-1188-CORE, Issue 1, June 2000

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

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


. Acknowledgments

   The previous author of this document was Derrick Dunne. The author
   would like to thank Derrick for his contributions.


. Author's Addresses

   Jason Collins
   Nortel Networks
   Ottawa, ON K1Y 4H7
   Phone: +1-613-768-4087
   Email: jcolli1@nortelnetworks.com




Collins                   Expires: 24/05/01                          5
                     Calling Line Identification         November 2000



. Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph
   are included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.































Collins                   Expires: 24/05/01                          6