Network Working Group E. Wilde Internet-Draft Swiss Federal Institute of Expires: January 12, 2005 Technology Jul 14, 2004 Registration of GSTN SMS Service Qualifier draft-wilde-sms-service-06 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 January 12, 2005. Copyright Notice Copyright (C) The Internet Society (2004). 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). Wilde Expires January 12, 2005 [Page 1] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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 1.2.3 SMS Telematic Interworking . . . . . . . . . . . . . . 5 2. IANA registrations . . . . . . . . . . . . . . . . . . . . . . 6 2.1 IANA registration form for GSTN address service-selector "SMS" . . . . . . . . . . . . . . . . . . 7 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 . . . . . . . . . . . . . . . . . 9 3. Security Considerations . . . . . . . . . . . . . . . . . . . 10 4. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1 From -00 to -01 . . . . . . . . . . . . . . . . . . . . . 11 4.2 From -01 to -02 . . . . . . . . . . . . . . . . . . . . . 11 4.3 From -02 to -03 . . . . . . . . . . . . . . . . . . . . . 11 4.4 From -03 to -04 . . . . . . . . . . . . . . . . . . . . . 12 4.5 From -04 to -05 . . . . . . . . . . . . . . . . . . . . . 12 4.6 From -05 to -06 . . . . . . . . . . . . . . . . . . . . . 12 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1 Normative References . . . . . . . . . . . . . . . . . . . . 12 5.2 Non-Normative References . . . . . . . . . . . . . . . . . . 13 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 13 A. Where to send Comments . . . . . . . . . . . . . . . . . . . . 13 B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . 14 Wilde Expires January 12, 2005 [Page 2] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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 many 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 70 character messages) MAY also be supported [SMS-CHAR], but are defined as being OPTIONAL by the SMS specification. Consequently, applications handling SMS messages as part of a chain of character processing applications MUST make sure that character sets are correctly mapped to and from the character set used for SMS messages. 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. Wilde Expires January 12, 2005 [Page 3] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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 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. SMS messages sent as with the GSTN SMS service MUST be sent as class 1 SMS messages, if the client is able to specify the message class. 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. Wilde Expires January 12, 2005 [Page 4] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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. 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 Wilde Expires January 12, 2005 [Page 5] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 "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) "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 The SMS specification fails to specify how X.400 OR addresses are actually embedded into SMS messages, so even though there is a Protocol Identifier for X.400, it is impossible to encode the recipient(s) of a message. email: Internet electronic mail The recipient(s) of SMS messages gatewayed to Internet electronic mail are specified in the message's user data in a way defined by the SMS specification. 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 Wilde Expires January 12, 2005 [Page 6] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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" qualif-type1 element's value (this may also mean that the GSTN address has to be ignored). For a complete description refer to RFC 3191 and draft-wilde-sms-service-06. Security Considerations: See the Security Consideration section of draft-wilde-sms-service-06. 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:erik.wilde@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" Wilde Expires January 12, 2005 [Page 7] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 qualif-type1 "keyword" name: SMSC qualif-type1 "value" ABNF definition: The ABNF definition for the value of the SMSC keyword is taken from RFC 3601 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-06 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-06. 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:erik.wilde@dret.net Wilde Expires January 12, 2005 [Page 8] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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: The ABNF syntax definition of the PID qualifier is as follows: sub-addr = "IMPL" / "TELEX" / "G3FAX" / "G4FAX" / "VOICE" / "ERMES" / "NATPAG" / "VIDEOTEX" / teletex / "UCI" / reserved / "MH" / "X400" / email / specific teletex = "TELETEX-" ( "UNSPEC" / "PSPDN" / "CSPDN" / "PSTN" / "ISDN" ) email = "SMTP:" address reserved = "RES" ( "1" / "2" / "3" / "4" / "5" / "6" / "7" ) specific = "SPEC" ( "1" / "2" / "3" / "4" / "5" / "6" / "7" ) The "x400" definition is functionally incomplete (because there is no way how the actual OR address can be specified), but provided here for completeness. 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-06 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-06. Person & email address to contact for further information: Wilde Expires January 12, 2005 [Page 9] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 Erik Wilde Swiss Federal Institute of Technology ETH-Zentrum 8092 Zurich Switzerland tel:+41-1-6325132 fax:+41-1-6321035 mailto:erik.wilde@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 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 Wilde Expires January 12, 2005 [Page 10] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 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 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. 4.2 From -01 to -02 o Removed address specification for X.400 SMS from ABNF (surprisingly not part of the SMS spec). o Added some explanatory text about character set mapping for SMS messages. o Added text requiring the use of message class 1 for sending SMS messages. 4.3 From -02 to -03 o Changed ordering of "change Log" section (descending to ascending). o Fixed some spelling errors. Wilde Expires January 12, 2005 [Page 11] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 4.4 From -03 to -04 o Updated reference to draft-allocchio-gstn (to revision -05). 4.5 From -04 to -05 o No changes, re-release for alignment with draft-wilde-sms-uri. 4.6 From -05 to -06 o Updated reference from draft-allocchio-gstn-05 to RFC 3601. 5. References 5.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [RFC2156] Kille, S., "MIXER (Mime Internet X.400 Enhanced Relay): Mapping between X.400 and RFC 822/MIME", RFC 2156, January 1998. [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. [RFC3601] Allocchio, C., "Text string notation for Dial Sequences and GSTN / E.164 addresses", RFC 3601, September 2003. [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, . [SMS-CHAR] European Telecommunications Standards Institute, "ETSI TS 100 901 (GSM 03.38 version 7.2.0 Release 1998): Digital Wilde Expires January 12, 2005 [Page 12] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 Cellular Telecommunications System (Phase 2+); Alphabets and language-specific information", July 1999, . [draft-wilde-sms-service-06] Wilde, E., "Registration of GSTN SMS Service Qualifier", draft-wilde-sms-service-06 (work in progress), Jul 2004. [draft-wilde-sms-uri-06] Wilde, E., "URI scheme for GSM Short Message Service", draft-wilde-sms-service-06 (work in progress), Jul 2004. 5.2 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: erik.wilde@dret.net URI: http://dret.net/netdret/ Appendix A. Where to send Comments Please send all comments and questions concerning this document to Erik Wilde. Appendix B. Acknowledgements This document has been prepared using the IETF document DTD described in RFC 2629 [RFC2629]. Thanks to Claudio Allocchio and Antti Vaha-Sipila for their comments. Wilde Expires January 12, 2005 [Page 13] Internet-Draft Registration of GSTN SMS Service Qualifier Jul 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. 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