One document matched: draft-ema-vpim-clid-06.txt
Differences from draft-ema-vpim-clid-05.txt
VPIM Working Group Glenn Parsons
Internet Draft Janusz Maruszak
Document: <draft-ema-vpim-clid-06.txt> Nortel Networks
Category: Standards Track January 2003
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.
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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. Two new
header fields are defined for this purpose: Caller ID and Called Name.
Caller ID is used to store sufficient information for the recipient to
callback, or reply to, the sender of the message. Called-name provides
the name of the person sending the message.
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Table of Contents
1. Introduction .................................................3
2. Conventions used in this document ............................3
3. Calling Line Identification Field ............................4
3.1 Internal Call ...............................................4
3.2 External Call ...............................................4
3.3 Numbering Plan ..............................................5
4. Caller Name Field ............................................5
5. Formal Syntax ................................................6
5.1 Calling Line Identification Syntax ..........................6
5.2 Caller Name Syntax ..........................................6
5.3 Examples ....................................................6
6. Security Considerations ......................................6
7. IANA Considerations ..........................................7
8. References ...................................................8
8.1 Normative References ........................................8
8.1 Informative References ......................................8
9. Acknowledgments ..............................................9
10. Author's Addresses ..........................................9
11. Full Copyright Statement ...................................10
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1. 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").
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.
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3. 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.
3.1 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.
3.2 External Call
For an international call, the calling party's 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
party's 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.
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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.
3.3 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 be
used to indicate the semantic. Only two semantics are defined "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.
4. 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 caller's 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].
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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].
5. 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]
5.1 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>
5.2 Caller Name Syntax
"Caller-Name" ":" unstructured CRLF
5.3 Examples
To: +19725551212@vm1.mycompany.com
Caller-ID: 6137684087
Caller-Name: Derrick Dunne
To: 6137637582@nortelnetworks.com
Caller-ID: 6139416900
Caller-Name: =?ISO-8859-1?Q?Jean_Chr=E9tien?=
6. Security Considerations
There are a few scenarios of how this mechanism may fail that must
be considered. The first is mentioned in section 3.2 - the truncation
of an international number to 10 digits. This could result in a
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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 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.
However, it must also be noted that this mechanism allows the
explicit indication of phone numbers in the headers of an email
message (used to store voice messages). While the rationale for this
is reviewed in section 1, the recipient of this message may not be
aware that this information is contained in the headers unless the
user's client presents the information. Its use is intended to be
informative as it is when it would appear on a telephone screen.
7. IANA Considerations
This document defines an IANA-administered registration space for
Caller-ID numbering plans in section 5.1. Each registry entry
consists of an identifying token and a short textual description of
the entry. There are two initial entries in this registry:
local - The number only has meaning within the FQDN of the
sending system identified by the RFC 2822 From field
of the message.
e164 - The number's semantics are described in [E.164].
The only way to add additional entries (ietf-token in section 5.1) to
this registry is with a standards-track RFC.
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8. References
8.1 Normative References
[VPIMV2R2] Vaudreuil, Greg, Parsons, Glenn, "Voice Profile for
Internet Mail, Version 2", <draft-ietf-vpimv2r2-05.txt>, February
2002.
[RFC2047] K. Moore, "MIME (Multipurpose Internet Mail Extensions)
Part Three : Message Header Extensions for Non-ASCII Text", RFC
2047, November 1996
[RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April
2001.
[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented
BNF for Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997
8.1 Informative References
[RFC2076] Palme, "Common Internet Message headers", RFC 2076,
February 1997
[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 (1998) (Withdrawn), "Character
Repertoire and Coded Character Sets for the International teletex
Service"
[8859-1] ISO/IEC International Standard 8859-1 (1998), Information
Technology - 8-bit single-byte coded graphic character sets -
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 Network-to-Customer Installation Interfaces -
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) -
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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 T1.641-1665
[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
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
Phone: +1-416-651-4448
Email: jjmaruszak@sympatico.ca
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11. Full Copyright Statement
Copyright (C) The Internet Society (2003). 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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