Network Working Group E. Wilde
Internet-Draft Swiss Federal Institute of
Expires: June 26, 2002 Technology
December 26, 2001
Registration of GSTN SMS Service Qualifier
draft-wilde-sms-service-00
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
This memo describes the registration of the Short Message Service
(SMS) as a registered IANA service selector for Global Switched
Telephone Network (GSTN) numbers. SMS is not available for all GSTN
subscribers, but it has proven very popular with users of the Global
System for Mobile Communications (GSM), and has also been adapted to
other telephone network technologies such as the Integrated Services
Digital Network (ISDN).
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 What is GSM? . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 What is SMS? . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1 SMS content . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.2 SMS infrastructure . . . . . . . . . . . . . . . . . . . . . 4
2. IANA registrations . . . . . . . . . . . . . . . . . . . . . 4
2.1 IANA registration form for GSTN address service-selector
"SMS" . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 IANA registration form for GSTN address qualit-type1 keyword
"SMSC" and value . . . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . 6
Normative References . . . . . . . . . . . . . . . . . . . . 7
Non-Normative References . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . 8
A. Where to send Comments . . . . . . . . . . . . . . . . . . . 8
B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
Full Copyright Statement . . . . . . . . . . . . . . . . . . 9
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1. Introduction
The capitalized 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 [RFC2119].
1.1 What is GSM?
GSM (Global System for Mobile Communications) is a digital mobile
phone standard which is used extensively in many parts of the world.
First named after its frequency band around 900 MHz, GSM-900 has
provided the basis for several other networks utilizing GSM
technology, in particular GSM networks operating in the frequency
bands around 1800 MHz and 1900 MHz. When referring to "GSM" in this
document, we mean any of these GSM-based networks that operate a
short message service.
1.2 What is SMS?
The Short Message Service [SMS] is an integral part of the GSM
network technology. It has been very successful and currently is a
major source of revenue for most GSM operators. SMS as a service is
so successful that other Global Switched Telephone Network (GSTN)
technologies have adapted it as well, in particular the Integrated
Services Digital Network (ISDN). Because of this development, this
memo uses the term "SMS client" to refer to user agents who are able
to send and/or receive SMS messages.
1.2.1 SMS content
GSM SMS messages are alphanumeric paging messages that can be sent to
and SMS clients. SMS messages have a maximum length of 160
characters (7-bit characters from the GSM character set [SMS-CHAR]),
or 140 octets. Other character sets (such as UCS-2 16-bit
characters, resulting in 80 character messages) MAY also be supported
[SMS-CHAR], but are defined as being OPTIONAL by the SMS
specification.
While the 160 character variety for SMS messages is by far the most
widely used one, there are numerous other content types for SMS
messages, such as small bitmaps ("operator logos") and simple formats
for musical notes ("ring tones"). However, these formats are
proprietary and are not considered in this memo.
SMS messages are very limited in length (140 octets), so several
methods exist to concatenate SMS messages. However, none of these
methods is standardized, and different manufacturers of mobile phones
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implement different methods of message concatenation. Therefore, SMS
message concatenation is not taken into consideration by this memo.
SMS clients composing messages may still employ concatenation
methods, but they MUST be aware that they do so at their own risk,
possibly using a method that is not supported by the receiving SMS
client.
1.2.2 SMS infrastructure
SMS messages can be transmitted over an SMS client's network
interface using the signalling channels of the underlying GSTN
infrastructure, so there is no delay for call setup. Alternatively,
SMS messages MAY be submitted through other front-ends (for example
such as Web services), which makes it possible for SMS clients to run
on computers which are not directly connected to a GSTN network
supporting SMS.
SMS messages are stored by an entity called Short Message Service
Centre (SMSC), and sent to the recipient when the subscriber connects
to the network. The number of a cooperative SMSC must be known to
the SMS sender (ie, the entity submitting the SMS message to a GSTN
infrastructure) when sending the message (usually, the SMSC's number
is configured in the SMS client and specific for the network operator
to which the sender has subscribed). In most situations, the SMSC
number is part of the sending SMS client's configuration. However,
in some special cases (such as when the SMS recipient only accepts
messages from a certain SMSC), it may be necessary to send the SMS
message over a specific SMSC.
Short messages can be mobile terminated (MT) or mobile originated
(MO). MT messages are the ones that arrive at SMS clients; MO
messages are sent by SMS clients. Networks may support either, both,
or none of these. For the purpose of this memo, it is important that
the sending SMS client is allowed to submit MO messages, and that the
receiver is allowed to receive MT messages.
The exact setup of message submission and delivery is not subject of
this memo, it may incorporate additional hops in addition to the pure
SMS transport. For example, the sending SMS client may use a Web
service to submit the SMS message, and the receiving SMS client may
be set up to forward the SMS to an email account. For the purpose of
this memo, it is important that the receiver can be addressed by a
GSTN number, and that the sender can submit an SMS message using this
number.
2. IANA registrations
Based on the requirements defined in RFC 3191 [RFC3191], the IANA
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registration forms for the "SMS" service-selector and "SMSC" qualif-
type1 elements are defined here. Syntax definitions are given using
the Augmented BNF for Syntax Specifications [RFC2234].
2.1 IANA registration form for GSTN address service-selector "SMS"
To: IANA@iana.org
Subject: Registration of new values for the GSTN address
service-selector specifier "SMS"
service-selector name: SMS
Description of Use: SMS - specify that the GSTN address refers to
a GSTN subscriber who is capable of receiving messages using
the GSM Short Message Service (SMS).
For a complete description refer to RFC 3191 and draft-wilde-
sms-service-00.
Security Considerations: See the Security Consideration section of
draft-wilde-sms-service-00.
Person & email address to contact for further information:
Erik Wilde
Swiss Federal Institute of Technology
ETH-Zentrum
8092 Zurich
Switzerland
tel:+41-1-6325132
fax:+41-1-6321035
mailto:ietf@dret.net
2.2 IANA registration form for GSTN address qualit-type1 keyword "SMSC"
and value
To: IANA@iana.org
Subject: Registration of new values for the GSTN address
qualif-type1 element "SMSC"
qualif-type1 "keyword" name: SMSC
qualif-type1 "value" ABNF definition: The ABNF definition for the
value of the SMSC keyword is taken from draft-allocchio-gstn-01
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sub-addr = gstn-phone
gstn-phone = ( global-phone / local-phone )
global-phone = "+" 1*( DIGIT / written-sep )
local-phone = [ exit-code ] dial-number / exit-code [ dial-number ]
exit-code = phone-string
dial-number = phone-string
phone-string = 1*( DTMF / pause / tonewait / written-sep )
DTMF = ( DIGIT / "#" / "*" / "A" / "B" / "C" / "D" )
pause = "p"
tonewait = "w"
written-sep = ( "-" / "." )
Description of Use: SMSC - In some situations, it may be necessary
to guide the sender of an SMS message to send the message via a
certain Short Message Service Center (SMSC). If the SMSC
qualif-type1 element is present, an SMS client SHOULD try to
send the message first using the specified SMSC. If that
fails, the SMS client MAY try another SMSC (such as the default
SMSC for that client).
Further description is available in draft-wilde-sms-service-00
Use Restriction: The use of the "SMSC" qualif-type1 element is
restricted to the "SMS" service-selector, it has no meaning
outside the SMS service defined by the "SMS" service-selector.
Security Considerations: See the Security Consideration section of
draft-wilde-sms-service-00.
Person & email address to contact for further information:
Erik Wilde
Swiss Federal Institute of Technology
ETH-Zentrum
8092 Zurich
Switzerland
tel:+41-1-6325132
fax:+41-1-6321035
mailto:ietf@dret.net
3. Security Considerations
SMS messages are transported without any provisions for privacy or
integrity, so SMS users should be aware of these inherent security
problems of SMS messages. Unlike electronic mail, where additional
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mechanisms exist to layer security features on top of the
infrastructure, there is no such framework for SMS messages.
SMS messages very often are delivered almost instantaneously (if the
receiving SMS client is on line), but there is no guarantee for when
SMS messages will be delivered. In particular, SMS messages between
different network operators sometimes take a long time to be
delivered (hours or even days) or are not delivered at all, so
applications SHOULD NOT make any assumptions about the reliability
and performance of SMS message transmission.
In most networks, sending SMS messages is not a free service.
Therefore, SMS clients MUST make sure that any action that incurs
costs is acknowledged by the end user, unless explicitly instructed
otherwise by the end user. If an SMS client has different ways of
submitting an SMS message (such as a Web service and a phone line),
then the end user MUST have a way to control which way is chosen.
SMS clients often are limited devices (typically mobile phones), and
the sending SMS client SHOULD NOT make any assumptions about the
receiving SMS client supporting any non-standard services, such as
message concatenation or proprietary content types. However, if the
sending SMS client has prior knowledge about the receiving SMS
client, then he MAY use this knowledge to compose non-standard SMS
messages.
Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs
to Indicate Requirement Levels", RFC
2119, March 1997.
[RFC2234] Crocker, D. and P. Overell, "Augmented
BNF for Syntax Specifications: ABNF",
RFC 2234, November 1997.
[RFC3191] Allocchio, C., "Minimal GSTN address
format in Internet Mail", RFC 3191,
October 2001.
[SMS] European Telecommunications Standards
Institute, "Digital Cellular
Telecommunications System (Phase 2+);
Technical realization of the Short
Message Service (SMS); Point-to-Point
(PP)", December 1998, <http://
pda.etsi.org/pda/home.asp?wki_id=6822>.
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[SMS-CHAR] European Telecommunications Standards
Institute, "Digital Cellular
Telecommunications System (Phase 2+)
(GSM); Alphabets and language-specific
information (GSM 03.38)", July 1996,
<http://pda.etsi.org/pda/
home.asp?wki_id=4690>.
[draft-allocchio-gstn] Allocchio, C., "Text string notation
for Dial Sequences and GSTN / E.164
addresses", draft-allocchio-gstn-01
(work in progress), November 2001.
[draft-wilde-sms-service-00] Wilde, E., "Registration of GSTN SMS
Service Qualifier", draft-wilde-sms-
service-00 (work in progress), December
2001.
Non-Normative References
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
Author's Address
Erik Wilde
Swiss Federal Institute of Technology
ETH-Zentrum
8092 Zurich
Switzerland
Phone: +41-1-6325132
EMail: ietf@dret.net
URI: http://dret.net/netdret/
Appendix A. Where to send Comments
Please send all comments about this document to Erik Wilde.
Appendix B. Acknowledgements
This document has been written using the IETF document DTD described
in RFC 2629 [RFC2629].
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