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Versions: 00 01 02 03 04 05 06 07 08 09 10 11                           
Network Working Group                                           E. Wilde
Internet-Draft                                Swiss Federal Institute of
Expires: July 17, 2002                                        Technology
                                                        January 16, 2002


               Registration of GSTN SMS Service Qualifier
                       draft-wilde-sms-service-01

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.

   This Internet-Draft will expire on July 17, 2002.

Copyright Notice

   Copyright (C) The Internet Society (2002).  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
   1.2.2.1 SMS Centers  . . . . . . . . . . . . . . . . . . . . . . .  4
   1.2.3   SMS Telematic Interworking . . . . . . . . . . . . . . . .  5
   2.      IANA registrations . . . . . . . . . . . . . . . . . . . .  6
   2.1     IANA registration form for GSTN address service-selector
           "SMS"  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   2.2     IANA registration form for GSTN address qualit-type1
           keyword "SMSC" and value . . . . . . . . . . . . . . . . .  7
   2.3     IANA registration form for GSTN address qualit-type1
           keyword "PID" and value  . . . . . . . . . . . . . . . . .  8
   3.      Security Considerations  . . . . . . . . . . . . . . . . .  9
   4.      Change Log . . . . . . . . . . . . . . . . . . . . . . . . 11
   4.1     From -00 to -01  . . . . . . . . . . . . . . . . . . . . . 11
           Normative References . . . . . . . . . . . . . . . . . . . 11
           Non-Normative References . . . . . . . . . . . . . . . . . 12
           Author's Address . . . . . . . . . . . . . . . . . . . . . 12
   A.      Where to send Comments . . . . . . . . . . . . . . . . . . 12
   B.      Acknowledgements . . . . . . . . . . . . . . . . . . . . . 12
           Full Copyright Statement . . . . . . . . . . . . . . . . . 13


























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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), and the first
   versions of the SMS specification did not specify any standardized
   methods for concatenating SMS messages.  As a consequence, several



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   proprietary methods were invented, but the current SMS specification
   does specify message concatenation.  In order to deal with this
   situation, SMS clients composing messages SHOULD use the standard
   concatenation method based on the header in the TP-User Data field as
   specified in [SMS].  When sending a message to an SMS recipient whose
   support for concatenated messages is unknown, the SMS client MAY opt
   to use the backwards-compatible (text-based) concatenation method
   defined in [SMS].  Proprietary concatenation methods SHOULD NOT be
   used except in closed systems, where the capabilities of the
   recipient(s) are always known.

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.

1.2.2.1 SMS Centers

   SMS messages are stored by an entity called Short Message Service
   Center (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



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   GSTN number, and that the sender can submit an SMS message using this
   number.

1.2.3 SMS Telematic Interworking

   While in most cases SMS messages are exchanged between SMS clients,
   the SMS specification also includes provisions for so-called
   "Telematic Interworking".  In this scenario, the SMS message
   specifies a Protocol Identifier, which identifies the service to
   which the SMS message has to be submitted.  In effect, this
   implements a gateway functionality in the SMSC.

   Telematic Interworking supports a number of services from Fax through
   Telex and Internet Email up to voice telephone, where the gateway is
   expected to make a text-to-speech transformation.  The set of
   possible services is defined by the SMS specification [SMS], but
   network operators are not required to support any of these services.
   SMS clients SHOULD implement support for Telematic Interworking,
   which among other things means that users must be able to set the
   Protocol Identifier field of generated SMS messages.  If clients
   support Telematic Interworking, they MUST indicate to the user the
   changed semantics of the receiver number (eg, if Fax is selected, the
   receiver will be contacted via Fax rather than SMS).

   In the following list the telematic devices (ie, the services that
   can be addressed using the Telematic Interworking mechanism) defined
   by the SMS specification are described.  The abbreviations are not
   taken from the SMS specification, but are introduced by this memo for
   identifying the device type using an SMS service qualifier keyword.

   "IMPL": In this case the device type is implicitly defined, either
      because the SMS Center knows it, or because it can be concluded on
      the basis of the address.

   "TELEX": Telex device

   "G3FAX": Group 3 telefax device

   "G4FAX": Group 4 telefax device

   "VOICE": Voice telephone (this requires conversion to speech, but
      there is no mechanism to specify a language)

   "ERMES": ERMES (European Radio Messaging System)

   "NATPAG": National paging system (this does not specify a specific
      paging systems but implies that the SMS center knows about a
      particular national paging system)



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   "VIDEOTEX": Videotex

   teletex: Teletex, either with an unspecified carrier or using PSPDN,
      CSPDN, PSTN, or ISDN as carrier

   "UCI": UCI (Universal Computer Interface)

   reserved: 7 combinations are reserved which do not have a specified
      meaning

   "MH": Some message handling facility known to the SMS center (not
      further specified)

   x400: X.400-based message handling system

   email: Internet electronic mail

   specific: 7 combinations are defined to have a meaning specific to
      each SMS center, their usage is based on mutual agreement between
      SMS clients and the SMS center.

   It is important to notice that some of the above devices require
   additional information to be specified (in particular, the "Internet
   electronic mail" format).  The SMS specification defines the methods
   how this has to be done (effectively by embedding the email
   information into the SMS message's text).

2. IANA registrations

   Based on the requirements defined in RFC 3191 [RFC3191], the IANA
   registration forms for the "SMS" service-selector, and "SMSC" and
   "PID" 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).  However, if a "PID" qualif-type1
      element is present for this service selector, then the GSTN
      address must be interpreted according to the rules for the "PID"



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      qualif-type1 element's value.

      For a complete description refer to RFC 3191 and draft-wilde-sms-
      service-01.

   Security Considerations: See the Security Consideration section of
      draft-wilde-sms-service-01.

   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



   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



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      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-01

   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-01.

   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


2.3 IANA registration form for GSTN address qualit-type1 keyword "PID"
    and value


   To:      IANA@iana.org
   Subject: Registration of new values for the GSTN address
            qualif-type1 element "PID"

   qualif-type1 "keyword" name: PID

   qualif-type1 "value" ABNF definition: ...












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   sub-addr      =  "IMPL" / "TELEX" / "G3FAX" / "G4FAX" / "VOICE"
                    / "ERMES" / "NATPAG" / "VIDEOTEX" / teletex / "UCI"
                    / reserved / "MH" / x400 / email / specific
   teletex       =  "TELETEX-"
                    ( "UNSPEC" / "PSPDN" / "CSPDN" / "PSTN" / "ISDN" )
   x400          =  "X400:" x400addr
   email         =  "SMTP:" address
   reserved      =  "RES" ( "1" / "2" / "3" / "4" / "5" / "6" / "7" )
   specific      =  "SPEC" ( "1" / "2" / "3" / "4" / "5" / "6" / "7" )

      The "x400addr" definition is taken from ...  (I am still looking
      for a reasonably agreed-upon textual representation of X.400 mail
      addresses...).

      The "address" definition is taken from RFC 2822 [RFC2822] and
      specifies an address that may either be an individual mailbox, or
      a group of mailboxes.

   Description of Use: PID - The protocol identifier is used to specify
      SMS Telematic Interworking by selecting a specific protocol to use
      for delivery to the recipient.

      Further description is available in draft-wilde-sms-service-01

   Use Restriction: The use of the "PID" 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-01.

   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 currently 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
   proprietary 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.

   There are certain special SMS messages defined in [SMS] that can be
   used, for example, to turn on indicators on the phone display, or to
   send data to certain communication ports (comparable to UDP ports) on
   the device.  Certain proprietary systems (for example, the Wireless
   Application Protocol [WAP])define configuration messages that may be
   used to reconfigure the devices remotely.  Any SMS client SHOULD make
   sure that malicious use of such messages is not possible, for example
   by filtering out certain SMS User Data headers.  Gateways that accept
   SMS messages e.g.  in e-mail messages or web forms and pass them on
   to an SMSC SHOULD implement this kind of 'firewalling' approach as
   well.

   Because the narrow bandwidth of the SMS communications channel, there
   should also be checks in place for excessively long concatenated
   messages.  As an example, it may take two minutes to transfer thirty
   concatenated text messages.

   Unchecked input from a user MUST NOT be used to populate any other
   fields in a Short Message other than the User Data field (not
   including the User Data Header field).  All other parts, including
   the User Data Header, of the Short Message should be generated by



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   trusted means.

4. Change Log

4.1 From -00 to -01

   o  Added a number of new security considerations

   o  Added the "PID" qualif-type1 keyword and the section about "SMS
      Telematic Interworking" Section 1.2.3

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.

   [RFC2822]                     Resnick, P., "Internet Message Format",
                                 RFC 2822, April 2001.

   [RFC3191]                     Allocchio, C., "Minimal GSTN address
                                 format in Internet Mail", RFC 3191,
                                 October 2001.

   [SMS]                         European Telecommunications Standards
                                 Institute, "ETSI TS 100 901 (GSM 03.40
                                 version 7.3.0 Release 1998): Digital
                                 Cellular Telecommunications System
                                 (Phase 2+); Technical realization of
                                 the Short Message Service (SMS); Point-
                                 to-Point (PP)", November 1999, <http://
                                 pda.etsi.org/pda/home.asp?wki_id=9942>.

   [SMS-CHAR]                    European Telecommunications Standards
                                 Institute, "ETSI TS 100 901 (GSM 03.38
                                 version 7.2.0 Release 1998): Digital
                                 Cellular Telecommunications System
                                 (Phase 2+); Alphabets and language-
                                 specific information", July 1999,
                                 <http://pda.etsi.org/pda/
                                 home.asp?wki_id=6821>.

   [draft-allocchio-gstn]        Allocchio, C., "Text string notation
                                 for Dial Sequences and GSTN / E.164



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                                 addresses", draft-allocchio-gstn-01
                                 (work in progress), November 2001.

   [draft-wilde-sms-service-01]  Wilde, E., "Registration of GSTN SMS
                                 Service Qualifier", draft-wilde-sms-
                                 service-01 (work in progress), January
                                 2002.

Non-Normative References

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [WAP]      WAP Forum, "Wireless Application Protocol - Architecture
              Specification (WAP-210-WAPArch-20010712)", July 2001.


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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Full Copyright Statement

   Copyright (C) The Internet Society (2002).  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
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   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
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   The limited permissions granted above are perpetual and will not be
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   This document and the information contained herein is provided on an
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   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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