INTERNET-DRAFT A. Vaha-Sipila Expires 27-Aug-1998 Nokia 23-Feb-1998 URLs for GSM Short Message Service 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 progress." To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast). Abstract This document specifies a URL (Uniform Resource Locator) scheme ''gsms'' 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 GSM, DCS, PCN and PCS . . . . . . . . . . . . . . . . . . 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 "gsms" URL Scheme . . . . . . . . . . . . . . . . . . 3 2.1 Applicability . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Formal Definition . . . . . . . . . . . . . . . . . . . . 3 2.3 Parsing a "gsms" URL . . . . . . . . . . . . . . . . . . . 4 2.4 Examples of Use . . . . . . . . . . . . . . . . . . . . . 4 3. References . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . 5 5. Authors' Addresses . . . . . . . . . . . . . . . . . . . . 5 1. Introduction 1.1 GSM, DCS, PCN and PCS A. Vaha-Sipila URLs for GSM Short Message Service February 1998 INTERNET-DRAFT Expires August, 1998 [Page 2] 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 "gsms" type URL is activated, the user agent MAY a program for sending an SMS message, just as "mailto" opens a mail client. A. Vaha-Sipila URLs for GSM Short Message Service February 1998 INTERNET-DRAFT Expires August, 1998 [Page 3] 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 "gsms" 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 [PSTN-ADDR] 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: sms-url = scheme ":" scheme-specific-part A. Vaha-Sipila URLs for GSM Short Message Service February 1998 INTERNET-DRAFT Expires August, 1998 [Page 4] scheme = "gsms" 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 "gsms" URL 1. 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. 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 gsms:+358551234567 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. gsms:+358551234567;via=+358551000100 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). [PSTN-ADDR] Minimal PSTN Address Format in Internet Mail. 1998. C. Allocchio. An Internet-Draft (work in progress). A. Vaha-Sipila URLs for GSM Short Message Service February 1998 INTERNET-DRAFT Expires August, 1998 [Page 5] [RFC2234] Augmented BNF for Syntax Specifications: ABNF. November 1997. D. Crocker et al. RFC 2234. [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. [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. [RFC2119] Key words for use in RFCs to Indicate Requirement Levels. April 1997. S. Bradner. 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 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 27th of August, 1998, or when a A. Vaha-Sipila URLs for GSM Short Message Service February 1998 INTERNET-DRAFT Expires August, 1998 [Page 6] new version is released. A. Vaha-Sipila URLs for GSM Short Message Service February 1998