ENUM R. Brandner
Internet-Draft Siemens AG
Expires: December 14, 2003 L. Conroy
Siemens Roke Manor Research
R. Stastny
Oefeg
June 15, 2003
Registration for enumservices of group messages
<draft-ietf-enum-msg-00.txt>
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document registers a group of 'enumservices' [5] to be used to
indicate that the associated resources are capable of receiving
discrete messages.
Specifically, the "enumservices" registered with this document are
'email', 'fax', 'sms', 'ems' and 'mms' using the URI schemes
'mailto:' and 'tel:'.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. E-mail Service Registration . . . . . . . . . . . . . . . . . 5
3. Fax Service Registration . . . . . . . . . . . . . . . . . . . 7
4. MMS, EMS, SMS Service . . . . . . . . . . . . . . . . . . . . 8
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2 SMS Service Registration . . . . . . . . . . . . . . . . . . . 8
4.3 EMS Service Registration . . . . . . . . . . . . . . . . . . . 9
4.4 MMS Service Registration . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13
References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . 16
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1. Introduction
ENUM (E.164 Number Mapping, RFC2916bis [5]) is a system that
transforms E.164 numbers [6] into domain names and then uses DNS
(Domain Name Service, RFC1034 [7]) services like delegation through
NS records and NAPTR records to look up what services are available
for a specific domain name.
This document registers 'enumservices' according to the guidelines
given in RFC2916bis to be used for provisioning in the services field
of a NAPTR [10] resource record to indicate what class of
functionality a given end point offers. The registration is defined
within the DDDS (Dynamic Delegation Discovery System
[9][10][11][12][13]) hierarchy, for use with the "E2U" DDDS
Application defined in RFC2916bis.
The following 'enumservices' are registered with this document:
'email', 'fax', 'sms', 'ems' and 'mms'. These share a common feature
in that they each indicate that the functionality of the given end
points and the associated resources are capable of receiving discrete
messages, albeit of different types.
According to RFC2619bis, the 'enumservice' registered must be able to
function as a selection mechanism when choosing one NAPTR resource
record from another. That means that the registration MUST specify
what is expected when using that very NAPTR record, and the URI
scheme which is the outcome of the use of it.
Therefore an 'enumservice' acts as a hint, indicating the kind of
service with which the URI constructed using the regexp field is
associated. There can be more than one 'enumservice' included within
a single NAPTR; this indicates that there is more than one service
that can be achieved using the associated URI scheme.
The common thread with this set of definitions is that they reflect
the kind of service that the end user will hope to achieve with the
communication using the associated URI.
The services specified here are intended NOT to specify the protocol
or even method of connection that MUST be used to achieve each
service. Instead they define the kind of interactive behavior that an
end user will expect, leaving the end system to decide (based on
policies outside the remit of this specification) how to execute the
service.
Since the same URI scheme may be used for different services (e.g.
'tel:'), and the same kind of service may use different URI schemes
(e.g. for VoIP 'h323:' and 'tel:' may be used), it is necessary in
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some cases to specify the service and the URI scheme used.
The service parameters defined in RFC2916bis allow therefore a 'type'
and a 'subtype' to be specified. Within this set of specifications
the convention is assumed that the 'type' (being the more generic
term) is defining the service and the 'subtype' is defining the URI
scheme.
Although currently only one URI scheme is associated with a given
service, it should be considered that an additional URI scheme to be
used with this service may be added later. Thus the subtype is needed
to identify the specific 'enumservice' intended.
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2. E-mail Service Registration
Enumservice Name: "email"
Type: "email"
Subtype: "mailto"
URI Scheme: 'mailto:'
Functional Specification:
This enumservice indicates that the remote resource can be addressed
by the associated URI scheme in order to send an email.
Security Considerations:
An e-mail address is a canonical address by which a user is known.
Placing this address in ENUM is comparable to placing a SIP or H.323
address in the DNS.
DNS does not make any policy decisions about the records that is
shares with an inquirer. All DNS records must be assumed to be
available to all inquirers at all times. The information provided
within an ENUM NAPTR resource record must therefore be considered to
be open to the public, which is a cause for some privacy
considerations.
Therefore ENUM Subscribers should be made aware of this risk. Since
it is within the responsibility of the ENUM Subscriber which data is
entered in ENUM, it is within the ENUM Subscribers control if he
enters e-mail addresses:
1. allowing inference of private data e.g. his first and last name
2. at all
It should also be considered that it is the purpose of public
communication identifiers to be publicly known. To reduce spam and
other unwanted communication other means should be made available.
See also Section 5.
Intended Usage: COMMON
Author:
Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact
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detail see Authors' Addresses section)
Any other information the author deems interesting:
None
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3. Fax Service Registration
Enumservice Name: "fax"
Type: "fax"
Subtype: "tel"
URI Scheme: 'tel:'
Functional Specification:
This enumservice indicates that the resource identified by the
associated URI scheme is capable of being contacted to provide a
communication session during which facsimile documents can be sent.
A client selecting this NAPTR will have support for generating and
sending facsimile documents to the recipient using the PSTN session
and transfer protocols specified in [2] and [3] - in short, they will
have a fax program with a local or shared PSTN access over which they
can send faxes.
Security Considerations:
An fax number as any other phone number may give not so much privacy
away then a name in the format user@host (e.g. an email or sip
address), but there is still the risk of unwanted messages. Therefore
in principle the same applies as stated in the security consideration
for e-mail.
See also Section 5.
Intended Usage: COMMON
Author:
Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact
detail see Authors' Addresses section)
Any other information the author deems interesting:
None
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4. MMS, EMS, SMS Service
4.1 Introduction
An ENUM NAPTR indicates ability on the part of the Subscriber to
receive specified communication service (or services) provided via
the contact address (shown in the generated URI).
In the case of MMS, EMS, and SMS services, the capability of these
services is a nested superset; thus a service supporting MMS can
support also delivery of EMS or SMS messages to a recipient, whilst a
service supporting EMS can also deliver SMS messages.
Thus, if a client is capable only of generating and sending an SMS
message, they MAY choose to consider also NAPTRs indicating support
for EMS and MMS services as well as SMS, as these services will be
able to deliver an SMS message to the recipient address.
Conversely, a client capable of sending MMS messages may choose to
consider also NAPTRs indicating support for EMS or SMS messages,
"downgrading" their User Interface to allow only generation of
messages that conform to SMS or EMS standards.
These behaviours on the part of the client are purely optional, and
are NOT the subject of any protocol standardization.
4.2 SMS Service Registration
Enumservice Name: "sms"
Type: "sms"
Subtype: "tel"
URI Scheme: 'tel:'
Functional Specification:
This enumservice indicates that the resource identified by the
associated URI scheme is capable of receiving a message using the
Short Message Service (SMS) [14].
Security Considerations:
There are no specific security issues with this 'enumservice'.
However, the general considerations of Section 5 apply.
Intended Usage: COMMON
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Author:
Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact
detail see Authors' Addresses section)
Any other information the author deems interesting:
None
4.3 EMS Service Registration
Enumservice Name: "ems"
Type: "ems"
Subtype: "tel"
URI Scheme: 'tel:'
Functional Specification:
This enumservice indicates that the resource identified by the
associated URI scheme is capable of receiving a message using the
Enhanced Message Service (EMS) [14].
Security Considerations:
There are no specific security issues with this 'enumservice'.
However, the general considerations of Section 5 apply.
Intended Usage: COMMON
Author:
Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact
detail see Authors' Addresses section)
Any other information the author deems interesting:
Note that an indication of EMS can be taken as implying that the
recipient is capable of receiving SMS messages at this address as
well.
4.4 MMS Service Registration
Enumservice Name: "mms"
Type: "mms"
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Subtype: "tel"
URI Scheme: 'tel:'
Functional Specification:
This enumservice indicates that the resource identified by the
associated URI scheme is capable of receiving a message using the
Multimedia Messaging Service (MMS) [15].
Security Considerations:
There are no specific security issues with this 'enumservice'.
However, the general considerations of Section 5 apply.
Intended Usage: COMMON
Author:
Rudolf Brandner, Lawrence Conroy, Richard Stastny (for author contact
detail see Authors' Addresses section)
Any other information the author deems interesting:
Note that MMS can be used as an alternative to deliver an SMS RP-DATA
RPDU if, for example, the SMS bearer is not supported. If an entry
includes this enumservice, then in effect this can be taken as
implying that the recipient is capable of receiving EMS or SMS
messages at this address. Such choices on the end system design do
have a small caveat; whilst in practise all terminals supporting MMS
today support SMS as well, it might not necessarily be the case in
the future. Also, MMS is under current development and so there may,
in the future, be other enumservices with type 'mms'.
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5. Security Considerations
DNS, as used by ENUM, is a global, distributed database. Thus any
information stored there is visible to anyone anonymously. Whilst
this is not qualitatively different from publication in a Telephone
Directory, it does open the data subject to having "their"
information collected automatically without any indication that this
has been done or by whom.
Such data harvesting by third parties is often used to generate lists
of targets for unrequested information; in short, they are used to
address "spam". Anyone who uses a Web-archived mailing list is aware
that the volume of "spam" email they are sent increases when they
post to the mailing list; publication of a telephone number in ENUM
is no different, and may be used to send "junk faxes" or "junk SMS"
for example.
Many mailing list users have more than one email address and use
"sacrificial" email accounts when posting to such lists to help
filter out unrequested emails sent to them. This is not so easy with
published telephone numbers; the PSTN E.164 number assignment process
is much more involved and usually a single E.164 number (or a fixed
range of numbers) is associated with each PSTN access. Thus providing
a "sacrificial" phone number in any publication is not possible.
Due to the implications of publishing data on a globally accessible
database, as a principle the data subject MUST give their explicit
informed consent to data being published in ENUM.
In addition, they should be made aware that, due to storage of such
data during harvesting by third parties, removal of the data from
publication will not remove any copies that have been taken; in
effect, any publication may be permanent.
However, regulations in many regions will require that the data
subject can at any time request that the data is removed from
publication, and that their consent for its publication is explicitly
confirmed at regular intervals.
When placing a fax call via the PSTN or a sending a message via the
Public Land Mobile Network, the sender may be charged for this
action. In both kinds of network, calling or messaging to some
numbers is more expensive than sending to others; both networks have
"premium rate" services that can charge considerably more than a
"normal" call or message destination. As such, it is important that
the end user be asked to confirm sending the message, and that the
destination number be presented to them. It is the originating user's
choice on whether or not to send a message to this destination
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number, but they SHOULD be shown the destination number so that they
can make this decision.
In addition to the specific security considerations given above, all
security considerations given in RFC2916bis apply.
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6. Acknowledgements
Many thanks to Ville Warsta for his close reading of the draft and
extracting the right references.
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References
[1] Bradner, S., "The Internet Standards Process -- Revision 3",
RFC 2026, BCP 9, October 1996.
[2] ITU-T, "Standardization of Group 3 facsimile terminals for
document transmission", T.4 , April 1999.
[3] ITU-T, "Procedures for document facsimile transmission in the
general switched telephone network", T.30 , April 1999.
[4] Schulzrinne, H. and A. Vaha-Sipila, "URIs for Telephone Calls",
draft-antti-RFC2806bis-08.txt , February 2003.
[5] Faltstrom, P. and M. Mealling, "The E.164 to URI DDDS
Application (ENUM)", draft-ietf-enum-rfc2916bis-06.txt , May
2003.
[6] ITU-T, "The International Public Telecommunication Number
Plan", Recommendation E.164 , May 1997.
[7] Mockapetris, P., "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC
1034, November 1987.
[8] ETSI, "Minimum Requirements for Interoperability of European
ENUM Trials", ETSI TS 102 172, February 2003.
[9] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
One: The Comprehensive DDDS", RFC 3401, October 2002.
[10] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
Two: The Algorithm", RFC 3402, October 2002.
[11] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
Three: The Domain Name System (DNS) Database", RFC 3403,
October 2002.
[12] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
Four: The Uniform Resource Identifiers (URI)", RFC 3404,
October 2002.
[13] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
Five: URI.ARPA Assignment Procedures", RFC 3405, October 2002.
[14] 3GPP, "Technical realization of the Short Message Service
(SMS); (Release5)", TS 23.040 .
[15] 3GPP, "Multimedia Messaging Service (MMS); Functional
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description; Stage 2 (Release 5)", TS 23.140 .
Authors' Addresses
Rudolf Brandner
Siemens AG
Hofmannstr. 51
81359 Munich
Germany
Phone: +49-89-722-51003
EMail: rudolf.brandner@siemens.com
Lawrence Conroy
Siemens Roke Manor Research
Roke Manor
Romsey
United Kingdom
Phone: +44-1794-833666
EMail: lwc@roke.co.uk
Richard Stastny
Oefeg
Postbox 147
1103 Vienna
Austria
Phone: +43-664-420-4100
EMail: Richard.stastny@oefeg.at
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