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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT                                           A. Vaha-Sipila
Expires 24-Nov-1999                                               Nokia
                                                            19-May-1999

                   URLs for GSM Short Message Service
                    <draft-antti-gsm-sms-url-04.txt>

Status of This Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   This document is an Internet-Draft. 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.

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   The distribution of this document before its expiry date is
   unlimited.

Abstract

   This document specifies a URL (Uniform Resource Locator) scheme "sms"
   for specifying a recipient for an alphanumeric message (Short
   Message) in a GSM-based mobile phone system. Short Messages are two-
   way paging messages that can be sent from a suitably equipped
   computer or a phone.











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Table of Contents

   1. Introduction ................................................    3

   1.1 What is GSM?  ..............................................    3

   1.2 Short Message Service ......................................    3

   1.3 Short Messages and the Internet ............................    3

   1.4 Formal Definitions .........................................    4

   1.5 Requirements ...............................................    4

   2. The "sms" URL Scheme ........................................    4

   2.1 Applicability ..............................................    4

   2.2 Formal Definition ..........................................    5

   2.3 Parsing a "sms" URL ........................................    5

   2.4 Examples of Use ............................................    6

   2.5 Using "sms" URLs in HTML Forms .............................    6

   3. References ..................................................    6

   4. Security Considerations .....................................    7

   5. Authors' Addresses ..........................................    8

   6. Full Copyright Statement ....................................    8














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1. Introduction

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.
   Named after its frequency band around 900 MHz, GSM-900 has provided
   the basis for several other networks utilizing GSM technology. When
   referring to "GSM" in this document, we mean any of these GSM-based
   networks that operate a short message service.

1.2 Short Message Service

   Short Messages [SMS] are two-way alphanumeric paging messages that
   can be sent to and from GSM mobile phones. Short Messages can be
   transmitted over the mobile phone's air interface using the
   signalling channels so there is no delay for call setup. Short
   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 sender
   when sending the message.

   Short Messages can be mobile terminated (MT) or mobile originated
   (MO). Mobile terminated messages are the ones that arrive to phones;
   mobile originating messages are sent by a mobile subscriber. Networks
   may support either, both or none of these.

   A service similar to GSM SMS can be found also in other mobile phone
   systems, but it may be called something else. The sender may not be
   able to know whether it is capable of successfully sending a Short
   Message to the recipient. The success depends on whether the network
   operators have a suitable roaming agreement and a mechanism to
   deliver the messages (theoretically it is possible to deliver short
   messages between different network types, but this is not common at
   the moment). It should be the network operator's responsibility to
   inform the user about a success or a failure of the message delivery.

   If there is a need to use the same scheme specifier for other network
   types than GSM, this document should be updated.

1.3 Short Messages and the Internet

   Short Messages can be used to transport almost any kind of data.
   Some examples of possible uses for a Short Message are described
   below.




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   The Hypertext Markup Language (HTML) provides a way to collect
   information from the user and pass it to a remote server for
   processing. This functionality is known as "forms". A filled-in form
   is usually sent to the destination using Hypertext Transfer Protocol
   (HTTP) or mail. Short Messages can be used as the transport for these
   forms. As the Short Message service is "out-of-band" as far as normal
   HTTP-over-TCP/IP is concerned, this provides a way to fill in forms
   offline and send the data without making a TCP connection to the
   remote server, as the set-up time, cost and overhead for a TCP
   connection are large compared to a Short Message. Also, depending on
   the network configuration, the sender's telephone number may be
   included in the Short Message, thus providing a weak form of
   authentication.

   Short Messages can also provide an alternative to a "mailto" type
   URL. When a "sms" type URL is activated, the user agent MAY start a
   program for sending an SMS message, just as "mailto" may open a mail
   client.

   The recipient need not to be a mobile phone. It can be a server that
   can process Short Messages, either by gatewaying them to another
   messaging system or by parsing them for supplementary services.

   GSM Short Messages have a maximum length of 160 characters (from the
   SMS character set), or 140 octets. However, Short Messages can be
   concatenated to form longer messages. It is up to the user agent to
   decide whether to limit the length of the message and how to indicate
   this limit in its user interface, if necessary. There is one
   exception to this, see section 2.5.

1.4 Formal Definitions

   Definitions are written using Augmented BNF for Syntax Specifications
   [RFC2234].

1.5 Requirements

   Compliant software MUST follow this specification. Requirements are
   indicated by capitalized words as specified in [RFC2119].

2. The "sms" URL Scheme

2.1 Applicability

   This URL scheme is intended for sending a Short Message to a certain
   recipient(s) through service centre(s). The functionality is quite



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   similar to that of the "mailto" URL, which (as per [RFC2368]) can
   also be used with a comma-separated list of email addresses.

   In some situations, it may be necessary to guide the sender to send
   the Short Message via a certain SMSC. For this purpose, this URL may
   specify the number of the SMSC.

   The notation for phone numbers is similar to that if [DRAFT-TELURL].
   Refer to that document and to [RFC2303] for information on why this
   particular format was chosen.

   How the Short Message is sent to the SMSC is outside the scope of
   this specification. Short Messages can be sent over the GSM air
   interface or by using a modem and a suitable protocol (such as UCP
   [UCP] or TDP [TDP]). Also, Short Message service options like
   deferred delivery and delivery notification requests are not in the
   scope of this document. Such services MAY be requested from the
   network by the user agent if necessary.

   Short Messages sent as a result of this URL MUST be sent as class 1
   Short Messages, if the user agent is able to specify the message
   class.

2.2 Formal Definition

   The URL is case-insensitive. The URL syntax is formally described as
   follows:

      sms-url              = scheme ":" scheme-specific-part
      scheme               = "sms"
      scheme-specific-part = subscriber-id [";via=" message-centre-id]
                             ["," scheme-specific-part]
      subscriber-id        = ["+"] phone-number
      message-centre-id    = ["+"] phone-number
      phone-number         = 1*phonedigit
      phonedigit           = digit / "-" / "."
      digit                = "0" / "1" / "2" / "3" / "4" / "5" /
                             "6" / "7" / "8" / "9"

2.3 Parsing a "sms" URL

   1. <subscriber-id> is extracted. It is the phone number of the final
   recipient and it MUST be written in international form with country
   code, unless the number only works from inside a certain geographical
   area or a network. Note that some numbers may work from several
   networks but not from the whole world - these SHOULD be written in



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   international form. All international numbers MUST begin with a "+"
   character. Hyphens and dots are only to aid readability. They MUST
   NOT have any other meaning.

   2. <message-centre-id> is extracted if present. User-agent SHOULD try
   to send the message first using this SMSC. If that fails, user-agent
   MAY try another SMSC. The number of the SMSC is subject to the same
   rules as the "subscriber-id" (see above).

   3. If the URL consists of a comma-separated list of recipients, all
   of them are processed in this manner. Exactly the same content SHOULD
   be sent to all of the listed recipients.

2.4 Examples of Use

      sms:+3585551234567

   This indicates a mobile terminated (MT) Short Message capable
   recipient at the given telephone number. The message is sent using
   the user-agent's default SMSC.

      sms:+3585551234567;via=+3585551000100

   This indicates that the Short Message should be sent using the SMSC
   at the given number.

2.5 Using "sms" URLs in HTML Forms

   When using a "sms" type URL as an action URL for HTML form submission
   [RFC1866], the form contents MUST be packaged in the Short Message
   just as they are packaged when using a "mailto" URL [RFC2368], using
   "application/x-www-form-urlencoded" MIME type [RFC1866]. The Short
   Message MUST NOT contain any HTTP headers, only the form data. The
   MIME type is implicit. It will not be transferred in the Short
   Message.

   The user agent SHOULD inform the user about the possible security
   hazards involved when submitting the form.

   If the form submission is longer than the maximum Short Message size,
   the user agent MAY either concatenate Short Messages, if it is able
   to do so, or it MAY refuse to send the message. The user agent MUST
   NOT send out partial form submissions.

3. References




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   [DRAFT-TELURL] URLs for Telephony. A. Vaha-Sipila. 1998.  An
   Internet-Draft (work in progress).  <ftp://ftp.nordu.net/internet-
   drafts/ draft-antti-telephony-url-05.txt>

   [RFC1738] Uniform Resource Locators (URL). December 1994. T.
   Berners-Lee et al. <ftp://ftp.nordu.net/rfc/rfc1738.txt>

   [RFC1866] Hypertext Markup Language - 2.0. T. Berners-Lee et al.
   November 1995. RFC 1866. <URL:ftp://ftp.nordu.net/rfc/rfc1866.txt>

   [RFC2119] Key words for use in RFCs to Indicate Requirement Levels.
   April 1997. S. Bradner.  <ftp://ftp.nordu.net/rfc/rfc2119.txt>

   [RFC2234] Augmented BNF for Syntax Specifications: ABNF. November
   1997. D. Crocker et al. RFC 2234.
   <URL:ftp://ftp.nordu.net/rfc/rfc2234.txt>

   [RFC2303] Minimal PSTN Address Format in Internet Mail. March 1998.
   C. Allocchio. RFC 2303.  <URL:ftp://ftp.nordu.net/rfc/rfc2303.txt>

   [RFC2368] The mailto URL Scheme. July 1998. P. Hoffman et al.  RFC
   2368. <URL:ftp://ftp.nordu.net/rfc/rfc2368.txt>

   [UCP] Paging Systems; European Radio Message System (ERMES) (ETS 300
   133-3). Part 3: Network Aspects. July 1992. European
   Telecommunications Standards Institute.

   [TDP] Telocator Data Paging Protocol (TDP). Version 2.0. July 27,
   1995. Personal Communications Industry Association.
   <http://www.mot.com/MIMS/MSPG/pcia_protocols/tdp_v2p0/index.html>

   [SMS] Digital Cellular Telecommunications System (Phase 2+):
   Technical Realization of the Short Message Service (SMS) Point-to-
   Point (PP) (GSM 3.40). Version 5.2.0. May 1996. European
   Telecommunications Standards Institute.

4. Security Considerations

   It should be noted that the user agent SHOULD NOT send out Short
   Messages without the knowledge of the user because of associated
   risks, which include sending masses of Short Messages to a subscriber
   without her consent and the costs involved in sending a Short
   Message.

   The user agent SHOULD have some mechanism that the user can use to
   filter out unwanted destinations for Short Messages. The user agent



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   SHOULD also have some means of restricting the number of Short
   Messages sent.

5. Authors' Addresses

   Contact person and version control responsibility for this
   specification:

      Nokia Mobile Phones
      Antti Vaha-Sipila
      P. O. Box 68
      FIN-33721 Tampere
      Finland

      Electronic mail: antti.vaha-sipila@nmp.nokia.com

   Please include your name and electronic mail address in all
   communications. If you want to receive the newest version of this
   specification electronically, send mail to the address above.

   This document expires on the 24th of November, 1999, or when a new
   version is released.

6. Full Copyright Statement

   To be included in the final RFC submission.























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