VPIM Working Group Glenn Parsons
Internet Draft Janusz Maruszak
Document: <draft-ema-vpim-clid-02.txt> Nortel Networks
Category: Standards Track June 2001
Calling Line Identification for Voice Mail Messages
Status of this Memo
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Abstract
This document describes a method for identifying the originating
calling party for 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 for 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.
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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").
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, 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 calling partyis 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
partyis 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.
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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 calleris 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 'unstructured' token defined in
[RFC2822]:
unstructured = *([FWS] utext) [FWS]
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6.1 Calling Line Identification Syntax
"Caller-ID" ":" unstructured CRLF
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.
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
[VPIMV2R2] Vaudreuil, Greg, Parsons, Glenn, "Voice Profile for Internet
Mail, version 2", <draft-ietf-vpim-vpimv2r2-03.txt>, June 2001.
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[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 n 8-bit single-byte coded graphic character sets n 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 n Network-to-Customer Installation Interfaces n
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) n
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 (2001). 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.
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Datatracker
draft-ema-vpim-clid-02
Internet-Draft
