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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT                                           A. Vaha-Sipila
Expires 27-Dec-1998                                               Nokia
                                                            22-Jun-1998

                  URLs for GSM Short Message Service
                   <draft-antti-gsm-sms-url-02.txt>

Status of This Memo

    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.

    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
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    (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu
    (US West Coast).

    Distribution of this memo is unlimited.

Abstract

    This document specifies a URL (Uniform Resource Locator) scheme
    'gsm-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 suitable
    equipped computer or a phone.

Contents

    1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . 1
    1.1 What is GSM? . . . . . . . . . . . . . . . . . . . . . . . 1
    1.2 Short Message Service  . . . . . . . . . . . . . . . . . . 2
    1.3 Short Messages and the Internet  . . . . . . . . . . . . . 2
    1.4 Formal Definitions . . . . . . . . . . . . . . . . . . . . 3
    1.5 Requirements . . . . . . . . . . . . . . . . . . . . . . . 3
    2.  The "gsm-sms" URL Scheme . . . . . . . . . . . . . . . . . 3
    2.1 Applicability  . . . . . . . . . . . . . . . . . . . . . . 3
    2.2 Formal Definition  . . . . . . . . . . . . . . . . . . . . 3
    2.3 Parsing a "gsm-sms" URL  . . . . . . . . . . . . . . . . . 4
    2.4 Examples of Use  . . . . . . . . . . . . . . . . . . . . . 4
    3.  References . . . . . . . . . . . . . . . . . . . . . . . . 4
    4.  Security Considerations  . . . . . . . . . . . . . . . . . 5
    5.  Authors' Addresses . . . . . . . . . . . . . . . . . . . . 5

1. Introduction

1.1 What is GSM?

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    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 are
    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. Because the user-agent must know whether it is
    capable of sending the message or not, the used system must be
    indicated somewhere in the URL. To keep everything simple, this
    document specifies a unique scheme specifier for a Short Message
    in the GSM system. Other systems MUST use other scheme specifiers.

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.

    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 "gsm-sms" type URL is activated, the user agent MAY
    start a program for sending an SMS message, just as "mailto" may

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    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.
    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.

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 "gsm-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 similar to that of the "mailto" URL, which (as per
    [RFC1738] only refers to one electronic mail address at a time,
    but is often 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.

2.2 Formal Definition

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


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    sms-url              = scheme ":" scheme-specific-part
    scheme               = "gsm-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 "gsm-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 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.

2.4 Examples of Use

        gsm-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.

        gsm-sms:+3585551234567;via=+3585551000100

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

3. References

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

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


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

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

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

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 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.


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    This document expires on the 27th of December, 1998, or when a
    new version is released.





















































A. Vaha-Sipila      URLs for GSM Short Message Service        June 1998