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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group E. Wilde 3 Internet-Draft Swiss Federal Institute of 4 Expires: July 25, 2002 Technology 5 A. Vaha-Sipila 6 Nokia 7 January 24, 2002 9 URI scheme for GSM Short Message Service 10 draft-wilde-sms-uri-01 12 Status of this Memo 14 This document is an Internet-Draft and is in full conformance with 15 all provisions of Section 10 of RFC2026. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at http:// 28 www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on July 25, 2002. 35 Copyright Notice 37 Copyright (C) The Internet Society (2002). All Rights Reserved. 39 Abstract 41 This memo specifies a URI (Universal Resource Identifier) scheme 42 "sms" for specifying a recipient (and optionally a gateway) for an 43 SMS message. SMS messages are two-way paging messages that can be 44 sent from and received by a mobile phone or a suitably equipped 45 computer. 47 Table of Contents 49 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 50 1.1 The Short Message Service . . . . . . . . . . . . . . . . . 3 51 1.2 Universal Resource Identifiers . . . . . . . . . . . . . . . 3 52 1.3 SMS Messages and the Internet . . . . . . . . . . . . . . . 3 53 1.3.1 SMS Messages and the Web . . . . . . . . . . . . . . . . . . 4 54 1.3.2 SMS Messages and Forms . . . . . . . . . . . . . . . . . . . 4 55 2. The "sms" URI Scheme . . . . . . . . . . . . . . . . . . . . 5 56 2.1 Applicability . . . . . . . . . . . . . . . . . . . . . . . 5 57 2.2 Formal Definition . . . . . . . . . . . . . . . . . . . . . 6 58 2.3 Parsing an "sms" URI . . . . . . . . . . . . . . . . . . . . 6 59 2.4 Examples of Use . . . . . . . . . . . . . . . . . . . . . . 7 60 2.5 Using "sms" URIs in HTML Forms . . . . . . . . . . . . . . . 8 61 3. "sms" URIs and SMS Web Services . . . . . . . . . . . . . . 8 62 3.1 Example . . . . . . . . . . . . . . . . . . . . . . . . . . 9 63 4. Security Considerations . . . . . . . . . . . . . . . . . . 9 64 5. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 10 65 5.1 From -00 to -01 . . . . . . . . . . . . . . . . . . . . . . 10 66 Normative References . . . . . . . . . . . . . . . . . . . . 11 67 Non-Normative References . . . . . . . . . . . . . . . . . . 12 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 12 69 A. Where to send Comments . . . . . . . . . . . . . . . . . . . 12 70 B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 71 Full Copyright Statement . . . . . . . . . . . . . . . . . . 14 73 1. Introduction 75 Compliant software MUST follow this specification. The capitalized 76 key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 77 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 78 document are to be interpreted as described in RFC 2119 [RFC2119]. 80 1.1 The Short Message Service 82 The Short Message Service (SMS) [SMS] is a rather simple service for 83 sending messages between SMS clients or, using so-called "Telematic 84 Interworking", from an SMS client through a gateway to a receiver 85 using a different service, such as fax or email. The SMS service is 86 described in more detail in the SMS service registration memo [draft- 87 wilde-sms-service-01]. 89 1.2 Universal Resource Identifiers 91 One of the core specifications for identifying resources on the 92 Internet is RFC 2396 [RFC2396], specifying the syntax and semantics 93 of a Universal Resource Identifier (URI). The most important notion 94 of URIs are "schemes", which define a framework within which 95 resources can be identified (and possibly accessed). URIs enable 96 users to identify resources, and are used for very diverse schemes 97 such as access protocols (HTTP, FTP), broadcast media (TV channels 98 [RFC2838]), messaging (email [RFC2368]), or even telephone numbers 99 (voice [RFC2806]). 101 URIs often are mentioned together with Universal Resource Names 102 (URNs) and/or Uniform Resource Locators (URLs), and it often is 103 unclear how to separate these concepts. For the purpose of this 104 memo, only the term URI will be used, referring to the most 105 fundamental concept. The World Wide Web Consortium (W3C) has issued 106 a note [uri-clarification] discussing the topic of URIs, URNs, and 107 URLs in detail. 109 1.3 SMS Messages and the Internet 111 One of the important reasons for the universal access of the Web is 112 the ability to access all information through a unique interface. 113 This kind of integration makes it easy to provide information as well 114 as to consume it. One aspect of this integration is the support of 115 user agents (in the case of the Web, commonly referred to as 116 browsers) for multiple content formats (such as HTML, GIF, JPEG) and 117 access schemes (such as HTTP, HTTP-S, FTP). 119 The "mailto" scheme has proven to be very useful and popular, because 120 most user agents support it by providing an email composition 121 facility when the user activates (eg, clicks on) the URI. 122 Accordingly, the "sms" scheme could be supported by user agents by 123 providing an SMS message composition facility when the user activates 124 the URI. Alternatively, in cases where the user agent does not 125 provide a built-in SMS message composition facility, the scheme could 126 still be supported by opening a Web page which provides such a 127 service. The specific Web page to be used could be configured by the 128 user, so that each user could use the SMS message composition service 129 of his choice. 131 This goal of this memo is to specify the "sms" URI scheme, so that 132 user agents (such as Web browsers and email clients) could start to 133 support it. 135 1.3.1 SMS Messages and the Web 137 SMS messages can provide an alternative to a "mailto" URIs [RFC2368], 138 or "tel" or "fax" URIs [RFC2806]. When a "sms" URI is activated, the 139 user agent MAY start a program for sending an SMS message, just as 140 "mailto" may open a mail client. Unfortunately, most browsers do not 141 support the external handling of internally unsupported URI schemes 142 in the same generalized way as most of them support external handling 143 of additional MIME type content for types which they do not support 144 internally. Ideally, user agents should implement generic URI 145 parsers and provide a way to associate unsupported schemes with 146 external applications (or Web services). 148 The recipient of an SMS message need not be a mobile phone. It can 149 be a server that can process SMS messages, either by gatewaying them 150 to another messaging system (such as regular electronic mail), or by 151 parsing them for supplementary services. 153 SMS messages can be used to transport almost any kind of data (even 154 though there is a very tight size limit), but the only standardized 155 data formats are character-based messages in different character 156 encodings. SMS messages have a maximum length of 160 characters 157 (when using 7-bit characters from the SMS character set), or 140 158 octets. However, SMS messages can be concatenated to form longer 159 messages. It is up to the user agent to decide whether to limit the 160 length of the message, and how to indicate this limit in its user 161 interface, if necessary. There is one exception to this, see Section 162 2.5. 164 1.3.2 SMS Messages and Forms 166 The Hypertext Markup Language (HTML) [HTML401] provides a way to 167 collect information from a user and pass it to a server for 168 processing. This functionality is known as "HTML forms". A filled- 169 in form is usually sent to the destination using the Hypertext 170 Transfer Protocol (HTTP) or email. However, SMS messages can also be 171 used as the transport mechanism for these forms. As SMS transport is 172 "out-of-band" as far as normal HTTP over TCP/IP is concerned, this 173 provides a way to fill in forms offline, and send the data without 174 making a TCP connection to the server, as the set-up time, cost, and 175 overhead for a TCP connection are large compared to an SMS message. 176 Also, depending on the network configuration, the sender's telephone 177 number may be included in the SMS message, thus providing a weak form 178 of authentication. 180 2. The "sms" URI Scheme 182 Syntax definitions are given using the Augmented BNF for Syntax 183 Specifications [RFC2234]. 185 2.1 Applicability 187 This URI scheme is intended for sending an SMS message to a certain 188 recipient(s). The functionality is quite similar to that of the 189 "mailto" URL, which (as per RFC 2368 [RFC2368]) can also be used with 190 a comma-separated list of email addresses. 192 In some situations, it may be necessary to guide the sender to send 193 the SMS message via a certain SMSC. For this purpose, the URI may 194 specify the number of the SMSC. 196 SMS messages may be sent through gateways to other services. These 197 gateways are operated inside SMS centers. An "SMS" URI may specify 198 that a certain gateway should be used. 200 The notation for phone numbers is taken from [draft-allocchio-gstn- 201 01]. Refer to this document for information on why this particular 202 format was chosen. 204 How the SMS message is sent to the SMSC is outside the scope of this 205 specification. SMS messages can be sent over the GSM air interface, 206 by using a modem and a suitable protocol, or by accessing services 207 over other protocols, such as a Web service for sending SMS messages. 208 Also, SMS message service options like deferred delivery and delivery 209 notification requests are not in the scope of this document. Such 210 services MAY be requested from the network by the user agent if 211 necessary. 213 SMS messages sent as a result of this URI MUST be sent as class 1 SMS 214 messages, if the user agent is able to specify the message class. 216 2.2 Formal Definition 218 The URI is case-insensitive. The syntax of an "sms" URI is formally 219 described as follows, where the base syntax is taken from RFC 2396 220 [RFC2396]: 222 sms-uri = scheme ":" scheme-specific-part 223 scheme = "sms" 224 scheme-specific-part = 1*( sms-recipient ) [ sms-body ] 225 sms-recipient = gstn-phone sms-qualifier 226 [ "," sms-recipient ] 227 sms-qualifier = *( smsc-qualifier / pid-qualifier ) 228 smsc-qualifier = ";smsc=" SMSC-sub-addr 229 pid-qualifier = ";pid=" PID-sub-addr 230 sms-body = ";body=" *urlc 232 The syntax definition for "gstn-phone" is taken from [draft- 233 allocchio-gstn-01], allowing global as well as local telephone 234 numbers. 236 The syntax definition for "SMSC-sub-addr" and "PID-sub-addr" is 237 derived from [draft-wilde-sms-service-01], please refer to that 238 document for the syntax of the qualifier values. 240 The "sms-body" is used to define the body of the SMS message to be 241 composed. It consists or URL-encoded characters. Only characters 242 from the 7-bit SMS character set [SMS-CHAR] are allowed. 244 It should be noted that both the SMSC as well as the PID qualifier 245 may appear only once per sms-recipient. If multiple qualifiers are 246 present, conforming software MUST interpret the first occurrence and 247 ignore all other occurrences. 249 2.3 Parsing an "sms" URI 251 The following list describes the steps for processing an "sms" URI: 253 1. The "gstn-phone" of the first "sms-recipient" is extracted. It 254 is the phone number of the final recipient and it MUST be written 255 in international form with country code, unless the number only 256 works from inside a certain geographical area or a network. Note 257 that some numbers may work from several networks but not from the 258 whole world - these SHOULD be written in international form. 259 According to [draft-allocchio-gstn-01], all international numbers 260 MUST begin with a "+" character. Hyphens and dots are only to 261 aid readability. They MUST NOT have any other meaning. 263 2. The "smsc-qualifier" of the first "sms-recipient" is extracted, 264 if present. 266 3. The "pid-qualifier" of the first "sms-recipient" is extracted, if 267 present. 269 4. The "sms-body" is extracted, if present. 271 5. The user agent should provide some means for message composition, 272 either by implementing this itself, or by accessing a service 273 providing it. Message composition SHOULD start with the body 274 extracted from the "sms-body", if present. If the "pid- 275 qualifier" is set to "pid=SMTP:...", then the user agents must 276 make sure that the email address is correctly set (as defined by 277 the SMS specification [SMS]) in the message being composed. 279 6. After message composition, a user agent SHOULD try to send the 280 message first using the SMSC set in the "smsc-qualifier" (if 281 present). If that fails, the user agent MAY try another SMSC. 283 7. If the URI consists of a comma-separated list of recipients (ie, 284 contains multiple "sms-recipient" parts), all of them are 285 processed in this manner. Exactly the same message SHOULD be 286 sent to all of the listed recipients. 288 2.4 Examples of Use 290 sms:+41796431851 292 This indicates an SMS message capable recipient at the given 293 telephone number. The message is sent using the user agent's default 294 SMSC. 296 sms:+41796431851;via=+41794999000 298 This indicates that the SMS message should be sent using the SMSC at 299 the given number. 301 sms:+41796431851,+4116321035;pid=fax 303 This URI should result in two SMS messages being sent, one to the 304 recipient number as shown in the example above, the other one being 305 sent as a fax to the second number (the fax is sent by the SMSC 306 performing the gatewaying, not by the user agent). 308 sms:+41796431851;pid=smtp:ietf@dret.net;body=hello%20there 309 In this case, a message (initially being set to "hello there", which 310 may have been modified by the user before sending) will be sent via 311 SMS using the SMS to email functionality in the SMSC, so that it will 312 eventually result in an email being sent to the specified email 313 address. In this case, the phone number will not be interpreted. 315 2.5 Using "sms" URIs in HTML Forms 317 When using a "sms" type URI as an action URI for HTML form submission 318 [HTML401], the form contents MUST be packaged in the SMS message just 319 as they are packaged when using a "mailto" URL [RFC2368], using the 320 "application/x-www-form-urlencoded" MIME type, effectively packaging 321 all form data into URI compliant syntax [RFC2396]. The SMS message 322 MUST NOT contain any HTTP headers, only the form data. The MIME type 323 is implicit. It MUST NOT be transferred in the SMS message. 325 The character encoding used for form submissions MUST be UTF-8 326 [RFC2279]. It should be noted, however, that user agents MUST URL- 327 encode form submissions before sending them. 329 The user agent SHOULD inform the user about the possible security 330 hazards involved when submitting the form (it is probably being sent 331 as plain text over an air interface). 333 If the form submission is longer than the maximum SMS message size, 334 the user agent MAY either concatenate SMS messages, if it is able to 335 do so, or it MAY refuse to send the message. The user agent MUST NOT 336 send out partial form submissions. 338 Form submission via an "sms" URI can be combined with Telematic 339 Interworking to result in form submissions being submitted via an SMS 340 message and finally being sent to an email account. In this case, 341 all provisions for using the email "pid-qualifier" and using "sms" 342 URIs with HTML forms must be followed. 344 3. "sms" URIs and SMS Web Services 346 In many cases, user agents will not be able to directly compose and 347 send SMS messages (because this requires that such a service is 348 accessible to the system the user agent is running on). However, it 349 is likely that the user has access to a Web service that provides an 350 SMS service, such as a Web site offering form-based SMS composition. 351 Ideally, the user agent should access this Web service when 352 activating an "sms" URI, thus enabling the user to use the Web 353 service. 355 One problem with this approach is that the Web service should somehow 356 get the "sms" URI, in order interpret it and set the required 357 parameters (such as the receiver's phone number). The easiest way to 358 implement this is for the user agent to add the "sms" URI as query 359 string to the Web service's URI. Consequently, user agents 360 supporting SMS Web services identified by URIs SHOULD append the 361 "sms" URI as query string to the Web services URI when accessing the 362 Web service. Web services providing SMS composition facilities 363 SHOULD expect to receive an "sms" URI as query string and should 364 process it as described by this memo. This method only can be 365 applied for Web service URIs which permit query strings (such as 366 "http" and "https" URIs). For other Web service URIs (such as "ftp" 367 and "mailto"), user agents as well as Web services MUST NOT use the 368 query string. 370 It should be noted that RFC 2396 [RFC2396] defines that within query 371 strings, the characters ";", "/", "?", ":", "@", "&", "=", "+", ",", 372 and "$" are reserved. It is therefore necessary to encode the "sms" 373 URI accordingly before appending it as query string. 375 3.1 Example 377 A document contains this piece of (X)HTML: 379 Send me an SMS! 381 The user agent interpreting this document does not internally support 382 SMS message composition, but has configured to access a Web service 383 for handling "sms" URIs. This Web service has the following URI: 385 http://sms.example.com/sms-form 387 When the user activates the "sms" URI (eg, by clicking on the text 388 "Send me an SMS!"), the user agents acts as if the activated URI had 389 been: 391 http://sms.example.com/sms-form?sms%3A%2B41796431851 393 The Web service is then responsible for parsing the query string and 394 providing an approriate interface, for example by already filling in 395 the recipient address with the number provided in the "sms" URI. 397 4. Security Considerations 399 The "Security Considerations" section of the SMS service registration 400 memo [draft-wilde-sms-service-01] MUST be consulted. 402 A user agent SHOULD NOT send out SMS messages without the knowledge 403 of the user, because of associated risks, which include sending 404 masses of SMS messages to a subscriber without his consent, and the 405 costs involved in sending an SMS message. 407 The user agent SHOULD have some mechanism that the user can use to 408 filter out unwanted destinations for SMS messages. The user agent 409 SHOULD also have some means of restricting the number of SMS messages 410 being sent as the result of activating one "sms" URI. 412 If an "sms" URI contains a pid-qualifier and the user agent supports 413 the qualifier and its value, then the user agent MUST set the SMS 414 message's PID as specified by the qualifier. User agents MAY inform 415 users about the value and the functional consequences of PID 416 qualifiers (eg, by notifying users that sending the SMS effectively 417 will result in a fax message being delivered, rather than an SMS 418 message). 420 The method described in section Section 3 adds another level of 421 indirection to the handling of "sms" URIs. If this method is 422 combined with the pid-qualifier gateway functionality, SMS 423 composition and reception will probably be distributed over three 424 different protocols (the Web service, SMS transport itself, and the 425 service selected by the pid-qualifier). User agent SHOULD make this 426 clear to users (either when the Web service is being configured, or 427 when it is accessed). 429 The Telematic Interworking functionality of the SMSC addressed by the 430 pid-qualifier is not necessarily implemented by the SMSC being used, 431 and SMSC providers are known for not or not correctly supporting some 432 or all pid-qualifier values. User agents SHOULD take into account 433 that the success rate of SMS messages being sent using pid-qualifiers 434 is lower than that of "plain" SMS messages. 436 5. Change Log 438 5.1 From -00 to -01 440 o Added the "sms-body" field and its processing rules. 442 o Added Section Section 3 about using "sms" URIs as query strings 443 for SMS Web services. 445 o Fixed typo in ABNF (said "global-phone" instead of "gstn-phone"). 447 o Added some explanatory text about form submissions using email 448 Telematic Interworking. 450 o Added some text about character encoding in form submissions. 452 Normative References 454 [HTML401] Raggett, D., Le Hors, A. and I. Jacobs, 455 "HTML 4.01 Specification", W3C REC- 456 html401, December 1999, . 459 [RFC2119] Bradner, S., "Key words for use in RFCs 460 to Indicate Requirement Levels", RFC 461 2119, March 1997. 463 [RFC2234] Crocker, D. and P. Overell, "Augmented 464 BNF for Syntax Specifications: ABNF", 465 RFC 2234, November 1997. 467 [RFC2279] Yergeau, F., "UTF-8, a transformation 468 format of ISO 10646", RFC 2279, January 469 1998. 471 [RFC2396] Berners-Lee, T., Fielding, R. and L. 472 Masinter, "Uniform Resource Identifiers 473 (URI): Generic Syntax", RFC 2396, 474 August 1998. 476 [SMS] European Telecommunications Standards 477 Institute, "Digital Cellular 478 Telecommunications System (Phase 2+); 479 Technical realization of the Short 480 Message Service (SMS); Point-to-Point 481 (PP)", December 1998, . 484 [SMS-CHAR] European Telecommunications Standards 485 Institute, "ETSI TS 100 901 (GSM 03.38 486 version 7.2.0 Release 1998): Digital 487 Cellular Telecommunications System 488 (Phase 2+); Alphabets and language- 489 specific information", July 1999, 490 . 493 [draft-allocchio-gstn-01] Allocchio, C., "Text string notation 494 for Dial Sequences and GSTN / E.164 495 addresses", draft-allocchio-gstn-01 496 (work in progress), November 2001. 498 [draft-wilde-sms-service-01] Wilde, E., "Registration of GSTN SMS 499 Service Qualifier", draft-wilde-sms- 500 service-01 (work in progress), January 501 2002. 503 Non-Normative References 505 [RFC2368] Hoffmann, P., Masinter, L. and J. Zawinski, "The 506 mailto URL scheme", RFC 2368, June 1998. 508 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 509 2629, June 1999. 511 [RFC2806] Vaha-Sipila, A., "URLs for Telephone Calls", RFC 512 2806, April 2000. 514 [RFC2838] Zigmond, D. and M. Vickers, "Uniform Resource 515 Identifiers for Television Broadcasts", RFC 516 2838, May 2000. 518 [uri-clarification] World Wide Web Consortium, "URIs, URLs, and 519 URNs: Clarifications and Recommendations 1.0", 520 W3C uri-clarification , September 2001, . 523 Authors' Addresses 525 Erik Wilde 526 Swiss Federal Institute of Technology 527 ETH-Zentrum 528 8092 Zurich 529 Switzerland 531 Phone: +41-1-6325132 532 EMail: ietf@dret.net 533 URI: http://dret.net/netdret/ 535 Antti Vaha-Sipila 536 Nokia 538 EMail: antti.vaha-sipila@nokia.com 540 Appendix A. Where to send Comments 542 Please send all comments about this document to Erik Wilde. 544 Appendix B. Acknowledgements 546 This document has been written using the IETF document DTD described 547 in RFC 2629 [RFC2629]. 549 Thanks to Claudio Allocchio for his comments. 551 Full Copyright Statement 553 Copyright (C) The Internet Society (2002). All Rights Reserved. 555 This document and translations of it may be copied and furnished to 556 others, and derivative works that comment on or otherwise explain it 557 or assist in its implementation may be prepared, copied, published 558 and distributed, in whole or in part, without restriction of any 559 kind, provided that the above copyright notice and this paragraph are 560 included on all such copies and derivative works. However, this 561 document itself may not be modified in any way, such as by removing 562 the copyright notice or references to the Internet Society or other 563 Internet organizations, except as needed for the purpose of 564 developing Internet standards in which case the procedures for 565 copyrights defined in the Internet Standards process must be 566 followed, or as required to translate it into languages other than 567 English. 569 The limited permissions granted above are perpetual and will not be 570 revoked by the Internet Society or its successors or assigns. 572 This document and the information contained herein is provided on an 573 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 574 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 575 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 576 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 577 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 579 Acknowledgement 581 Funding for the RFC Editor function is currently provided by the 582 Internet Society.