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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (Jun 6, 2008) is 5802 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC2822' is defined on line 818, but no explicit reference was found in the text -- Possible downref: Non-RFC (?) normative reference: ref. 'HTML401' ** Obsolete normative reference: RFC 2822 (Obsoleted by RFC 5322) ** Obsolete normative reference: RFC 4395 (Obsoleted by RFC 7595) -- Possible downref: Non-RFC (?) normative reference: ref. 'SMS' -- Possible downref: Non-RFC (?) normative reference: ref. 'SMS-CHAR' -- Obsolete informational reference (is this intentional?): RFC 2368 (Obsoleted by RFC 6068) -- Obsolete informational reference (is this intentional?): RFC 2629 (Obsoleted by RFC 7749) Summary: 3 errors (**), 0 flaws (~~), 3 warnings (==), 12 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group E. Wilde 3 Internet-Draft UC Berkeley 4 Intended status: Standards Track A. Vaha-Sipila 5 Expires: December 8, 2008 Nokia 6 Jun 6, 2008 8 URI Scheme for GSM Short Message Service 9 draft-wilde-sms-uri-15 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on December 8, 2008. 36 Abstract 38 This memo specifies the Uniform Resource Identifier (URI) scheme 39 "sms" for specifying one or more recipients for an SMS message. SMS 40 messages are two-way paging messages that can be sent from and 41 received by a mobile phone or a suitably equipped networked device. 43 Table of Contents 45 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 46 1.1. What is GSM? . . . . . . . . . . . . . . . . . . . . . . . 3 47 1.2. What is SMS? . . . . . . . . . . . . . . . . . . . . . . . 3 48 1.3. The "sms" URI Scheme . . . . . . . . . . . . . . . . . . . 7 49 2. URI Scheme Registration . . . . . . . . . . . . . . . . . . . 10 50 2.1. URI Scheme Name . . . . . . . . . . . . . . . . . . . . . 10 51 2.2. Status . . . . . . . . . . . . . . . . . . . . . . . . . . 10 52 2.3. URI Scheme Syntax . . . . . . . . . . . . . . . . . . . . 10 53 2.4. URI Scheme Semantics . . . . . . . . . . . . . . . . . . . 10 54 2.5. Encoding Considerations . . . . . . . . . . . . . . . . . 11 55 2.6. Applications/Protocols that use this URI Scheme Name . . . 11 56 2.7. Interoperability Considerations . . . . . . . . . . . . . 11 57 2.8. Security Considerations . . . . . . . . . . . . . . . . . 11 58 2.9. Contact . . . . . . . . . . . . . . . . . . . . . . . . . 11 59 3. Security Considerations . . . . . . . . . . . . . . . . . . . 11 60 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 61 5. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 13 62 5.1. From -14 to -15 . . . . . . . . . . . . . . . . . . . . . 13 63 5.2. From -13 to -14 . . . . . . . . . . . . . . . . . . . . . 14 64 5.3. From -12 to -13 . . . . . . . . . . . . . . . . . . . . . 14 65 5.4. From -11 to -12 . . . . . . . . . . . . . . . . . . . . . 14 66 5.5. From -10 to -11 . . . . . . . . . . . . . . . . . . . . . 15 67 5.6. From -09 to -10 . . . . . . . . . . . . . . . . . . . . . 15 68 5.7. From -08 to -09 . . . . . . . . . . . . . . . . . . . . . 15 69 5.8. From -07 to -08 . . . . . . . . . . . . . . . . . . . . . 15 70 5.9. From -06 to -07 . . . . . . . . . . . . . . . . . . . . . 15 71 5.10. From -05 to -06 . . . . . . . . . . . . . . . . . . . . . 15 72 5.11. From -04 to -05 . . . . . . . . . . . . . . . . . . . . . 15 73 5.12. From -03 to -04 . . . . . . . . . . . . . . . . . . . . . 16 74 5.13. From -02 to -03 . . . . . . . . . . . . . . . . . . . . . 16 75 5.14. From -01 to -02 . . . . . . . . . . . . . . . . . . . . . 16 76 5.15. From -00 to -01 . . . . . . . . . . . . . . . . . . . . . 16 77 5.16. Change Log of draft-wilde-sms-service . . . . . . . . . . 16 78 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 79 6.1. Normative References . . . . . . . . . . . . . . . . . . . 18 80 6.2. Non-Normative References . . . . . . . . . . . . . . . . . 19 81 Appendix A. Where to send Comments . . . . . . . . . . . . . . . 19 82 Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 19 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 84 Intellectual Property and Copyright Statements . . . . . . . . . . 21 86 1. Introduction 88 Compliant software MUST follow this specification. The capitalized 89 key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 90 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 91 document are to be interpreted as described in RFC 2119 [RFC2119]. 93 1.1. What is GSM? 95 GSM (Global System for Mobile Communications) is a digital mobile 96 phone standard which is used extensively in many parts of the world. 97 First named after its frequency band around 900 MHz, GSM-900 has 98 provided the basis for several other networks utilizing GSM 99 technology, in particular GSM networks operating in the frequency 100 bands around 1800 MHz and 1900 MHz. When referring to "GSM" in this 101 document, we mean any of these GSM-based networks that operate a 102 short message service. 104 1.2. What is SMS? 106 The Short Message Service (SMS) [SMS] is an integral part of the GSM 107 network technology. It has been very successful and currently is a 108 major source of revenue for many GSM operators. SMS as a service is 109 so successful that other Global Switched Telephone Network (GSTN) 110 technologies have adapted it as well, in particular the Integrated 111 Services Digital Network (ISDN). Because of this development, this 112 memo uses the term "SMS client" to refer to user agents who are able 113 to send and/or receive SMS messages. 115 1.2.1. SMS content 117 GSM SMS messages are alphanumeric paging messages that can be sent to 118 and from SMS clients. SMS messages have a maximum length of 160 119 characters (7-bit characters from the GSM character set [SMS-CHAR]), 120 or 140 octets. Other character sets (such as UCS-2 16-bit 121 characters, resulting in 70 character messages) MAY also be supported 122 [SMS-CHAR], but are defined as being optional by the SMS 123 specification. Consequently, applications handling SMS messages as 124 part of a chain of character processing applications MUST make sure 125 that character sets are correctly mapped to and from the character 126 set used for SMS messages. 128 While the 160 character variety for SMS messages is by far the most 129 widely used one, there are numerous other content types for SMS 130 messages, such as small bitmaps ("operator logos") and simple formats 131 for musical notes ("ring tones"). However, these formats are 132 proprietary and are not considered in this memo. 134 SMS messages are very limited in length (140 octets), and the first 135 versions of the SMS specification did not specify any standardized 136 methods for concatenating SMS messages. As a consequence, several 137 proprietary methods were invented, but the current SMS specification 138 does specify message concatenation. In order to deal with this 139 situation, SMS clients composing messages SHOULD use the standard 140 concatenation method based on the header in the TP-User Data field as 141 specified in the SMS specification [SMS]. When sending a message to 142 an SMS recipient whose support for concatenated messages is unknown, 143 the SMS client MAY opt to use the backwards-compatible (text-based) 144 concatenation method defined in the SMS specification [SMS]. 145 Proprietary concatenation methods SHOULD NOT be used except in closed 146 systems, where the capabilities of the recipient(s) are always known. 148 1.2.2. SMS infrastructure 150 SMS messages can be transmitted over an SMS client's network 151 interface using the signaling channels of the underlying GSTN 152 infrastructure, so there is no delay for call setup. Alternatively, 153 SMS messages may be submitted through other front-ends (for example 154 Web-based services), which makes it possible for SMS clients to run 155 on computers which are not directly connected to a GSTN network 156 supporting SMS. 158 SMS messages sent with the GSTN SMS service MUST be sent as class 1 159 SMS messages, if the client is able to specify the message class. 161 1.2.2.1. SMS Centers 163 For delivery within GSTN networks, SMS messages are stored by an 164 entity called SMS Center (SMSC), and sent to the recipient when the 165 subscriber connects to the network. The number of a cooperative SMSC 166 must be known to the SMS sender (i.e., the entity submitting the SMS 167 message to a GSTN infrastructure) when sending the message (usually, 168 the SMSC's number is configured in the SMS client and specific for 169 the network operator to which the sender has subscribed). In most 170 situations, the SMSC number is part of the sending SMS client's 171 configuration. However, in some special cases (such as when the SMS 172 recipient only accepts messages from a certain SMSC), it may be 173 necessary to send the SMS message over a specific SMSC. The scheme 174 specified in this memo does not support the specification of SMSC 175 numbers, so in case of scenarios where messages have to be sent 176 through a certain SMSC, there must be some other context establishing 177 this requirement, or message delivery may fail. 179 Short messages can be mobile terminated (MT) or mobile originated 180 (MO). MT messages are the ones that arrive at SMS clients; MO 181 messages are sent by SMS clients. Networks may support either, both, 182 or none of these. For the purpose of this memo, it is important that 183 the sending SMS client is allowed to submit MO messages, and that the 184 receiver is allowed to receive MT messages. 186 The exact setup of message submission and delivery is outside the 187 scope of this memo, it may incorporate additional hops in addition to 188 the pure SMS transport. For example, the sending SMS client may use 189 a Web-based service to submit the SMS message, and the receiving SMS 190 client may be set up to forward the SMS to an email account. For the 191 purpose of this memo, it is important that the receiver can be 192 addressed by a GSTN number, and that the sender can submit an SMS 193 message using this number. 195 1.2.3. Uniform Resource Identifiers 197 One of the core specifications for identifying resources on the 198 Internet is RFC 3986 [RFC3986], specifying the syntax and semantics 199 of a Uniform Resource Identifier (URI). The most important notion of 200 URIs are "schemes", which define a framework within which resources 201 can be uniquely identified and addressed. URIs enable users to 202 access resources, and are used for very diverse schemes such as 203 access protocols (HTTP, FTP), broadcast media (TV channels 204 [RFC2838]), messaging (email [RFC2368]), and even telephone numbers 205 (voice [RFC3966]). 207 URIs often are mentioned together with Uniform Resource Names (URNs) 208 and/or Uniform Resource Locators (URLs), and it often is unclear how 209 to separate these concepts. For the purpose of this memo, only the 210 term URI will be used, referring to the most fundamental concept. 211 The World Wide Web Consortium (W3C) has issued a note 212 [uri-clarification] discussing the topic of URIs, URNs, and URLs in 213 detail. 215 1.2.4. SMS Messages and the Internet 217 One of the important reasons for the universal access of the Web is 218 the ability to access all information through a unique interface. 219 This kind of integration makes it easy to provide information as well 220 as to consume it. One aspect of this integration is the support of 221 user agents (in the case of the Web, commonly referred to as 222 browsers) for multiple content formats (such as HTML, GIF, JPEG) and 223 access schemes (such as HTTP, HTTPS, FTP). 225 The "mailto" scheme has proven to be very useful and popular, because 226 most user agents support it by providing an email composition 227 facility when the user selects (e.g., clicks on) the URI. Similarly, 228 the "sms" scheme can be supported by user agents by providing an SMS 229 message composition facility when the user selects the URI. In cases 230 where the user agent does not provide a built-in SMS message 231 composition facility, the scheme could still be supported by opening 232 a Web page which provides such a service. The specific Web page to 233 be used could be configured by the user, so that each user could use 234 the SMS message composition service of his choice. 236 The goal of this memo is to specify the "sms" URI scheme, so that 237 user agents (such as Web browsers and email clients) can start to 238 support it. The "sms" URI scheme identifies SMS message endpoints as 239 resources. When "sms" URIs are dereferenced, implementations MAY 240 create a message and present it to be edited before being sent, or 241 they MAY invoke additional services to provide the functionality 242 necessary for composing a message and sending it to the SMS message 243 endpoint. In either case, simply activating a link with an "sms" URI 244 SHOULD NOT cause a message to be sent without prior user 245 confirmation. 247 1.2.4.1. SMS Messages and the Web 249 SMS messages can provide an alternative to "mailto" URIs [RFC2368], 250 or "tel" or "fax" URIs [RFC3966]. When a "sms" URI is activated, the 251 user agent MAY start a program for sending an SMS message, just as 252 "mailto" may open a mail client. Unfortunately, most browsers do not 253 support the external handling of internally unsupported URI schemes 254 in the same generalized way as most of them support external handling 255 of content for media types which they do not support internally. 256 Ideally, user agents should implement generic URI parsers and provide 257 a way to associate unsupported schemes with external applications (or 258 Web-based services). 260 The recipient of an SMS message need not be a mobile phone. It can 261 be a server that can process SMS messages, either by gatewaying them 262 to another messaging system (such as regular electronic mail), or by 263 parsing them for supplementary services. 265 SMS messages can be used to transport almost any kind of data (even 266 though there is a very tight size limit), but the only standardized 267 data formats are character-based messages in different character 268 encodings. SMS messages have a maximum length of 160 characters 269 (when using 7-bit characters from the SMS character set), or 140 270 octets. However, SMS messages can be concatenated to form longer 271 messages. It is up to the user agent to decide whether to limit the 272 length of the message, and how to indicate this limit in its user 273 interface, if necessary. There is one exception to this, see 274 Section 1.3.5. 276 1.2.4.2. SMS Messages and Forms 278 The Hypertext Markup Language (HTML) [HTML401] provides a way to 279 collect information from a user and pass it to a server for 280 processing. This functionality is known as "HTML forms". A 281 filled-in form is usually sent to the destination using the Hypertext 282 Transfer Protocol (HTTP) or email. However, SMS messages can also be 283 used as the transport mechanism for these forms. As SMS transport is 284 "out-of-band" as far as normal HTTP over TCP/IP is concerned, this 285 provides a way to fill in forms offline, and send the data without 286 making a TCP connection to the server, as the set-up time, cost, and 287 overhead for a TCP connection are large compared to an SMS message. 288 Also, depending on the network configuration, the sender's telephone 289 number may be included in the SMS message, thus providing a weak form 290 of authentication. 292 1.3. The "sms" URI Scheme 294 Syntax definitions are given using the Augmented BNF (ABNF) for 295 syntax specifications [RFC5234]. 297 1.3.1. Applicability 299 This URI scheme provides information that can be used for sending an 300 SMS message to certain recipient(s). The functionality is comparable 301 to that of the "mailto" URI, which (as per RFC 2368 [RFC2368]) can 302 also be used with a comma-separated list of email addresses. 304 The notation for phone numbers is taken from [RFC3966]. Refer to 305 this document for information on why this particular format was 306 chosen. 308 How the SMS message is sent to the SMSC or other intermediaries is 309 outside the scope of this specification. SMS messages can be sent 310 over the GSM air interface, by using a modem and a suitable protocol, 311 or by accessing services over other protocols, such as a Web-based 312 service for sending SMS messages. Also, SMS message service options 313 like deferred delivery and delivery notification requests are not 314 within the scope of this document. Such services MAY be requested 315 from the network by the user agent if necessary. 317 SMS messages sent as a result of this URI MUST be sent as class 1 SMS 318 messages, if the user agent is able to specify the message class. 320 1.3.2. Formal Definition 322 The URI scheme's keywords specified in the following syntax 323 description are case-insensitive. The syntax of an "sms" URI is 324 formally described as follows, where the URI base syntax is taken 325 from RFC 3986 [RFC3986]: 327 sms-uri = scheme ":" hier-part [ "?" sms-body ] 328 scheme = "sms" 329 hier-part = sms-recipient *( "," sms-recipient ) 330 sms-recipient = sms-number 331 sms-number = ( global-number / local-number ) 332 global-number = "+" local-number 333 local-number = *phonedigit DIGIT *phonedigit 334 sms-body = "body=" query 336 Some illustrative examples using this syntax are given in 337 Section 1.3.4. 339 The syntax definition for is taken from RFC 3966 340 [RFC3966]. 342 The syntax definition for is taken from RFC 3986 [RFC3986], 343 please refer to that document. 345 The is used to define the body of the SMS message to be 346 composed. It consists of percent-encoded UTF-8 characters. 347 Implementations MUST make sure that the characters are 348 converted to a suitable character encoding before sending, the most 349 popular being the 7-bit SMS character encoding, another variant 350 (though not as universally supported as 7-bit SMS) is the UCS-2 351 character encoding (both specified in [SMS-CHAR]). Implementations 352 MAY choose to discard (or convert) characters in the that 353 are not supported by the SMS character set they are using to send the 354 SMS message. If they do discard or convert characters, they MUST 355 notify the user. 357 User agents SHOULD support multiple recipients, and SHOULD make it 358 clear to users what the entire list of recipients is, before 359 committing the user to sending all the messages. 361 1.3.3. Processing an "sms" URI 363 The following list describes the steps for processing an "sms" URI: 365 1. The of the first is extracted. It 366 is the phone number of the final recipient and it MUST be written 367 in international form with country code, unless the number only 368 works from inside a certain geographical area or a network. Note 369 that some numbers may work from several networks but not from the 370 whole world - these SHOULD be written in international form. 372 According to RFC 3966 [RFC3966], all international numbers MUST 373 begin with a "+" character. Hyphens, dots, and parentheses 374 (referred to as "visual separators" in RFC 3966) are used only to 375 improve readability and MUST NOT convey any other meaning. 377 2. The is extracted, if present. 379 3. The user agent should provide some means for message composition, 380 either by implementing this itself, or by accessing a service 381 providing it. Message composition SHOULD start with the body 382 extracted from the , if present. 384 4. After message composition, a user agent SHOULD try to send the 385 message first using the default delivery method employed by that 386 user agent. If that fails, the user agent MAY try another 387 delivery method. 389 5. If the URI consists of a comma-separated list of recipients 390 (i.e., contains multiple parts), all of them are 391 processed in this manner. Exactly the same message SHOULD be 392 sent to all of the listed recipients, which means that the 393 message resulting from the message composition step for the first 394 recipient is used unaltered for all other recipients as well. 396 1.3.4. Examples of Use 398 sms:+12024561111 400 This indicates an SMS message capable recipient at the given 401 telephone number. The message is sent using the user agent's default 402 SMS delivery method. 404 sms:+12024561111,+15102061079 406 This indicates SMS message capable recipients at the given telephone 407 numbers. The identical message should be sent to both recipients 408 using the user agent's default SMS delivery method. 410 sms:+12024561111?body=hello%20there 412 In this case, a message (initially being set to "hello there", which 413 may be modified by the user before sending) will be sent via SMS 414 using the user agent's default SMS delivery method. 416 1.3.5. Using "sms" URIs in HTML Forms 418 When using a "sms" type URI as an action URI for HTML form submission 419 [HTML401], the form contents MUST be packaged in the SMS message just 420 as they are packaged when using a "mailto" URI [RFC2368], using the 421 "application/x-www-form-urlencoded" media type, effectively packaging 422 all form data into URI compliant syntax [RFC3986]. The SMS message 423 MUST NOT contain any HTTP headers, only the form data. The media 424 type is implicit. It MUST NOT be transferred in the SMS message. 426 The character encoding used for form submissions MUST be UTF-8 427 [RFC3629]. It should be noted, however, that user agents MUST 428 percent-encode form submissions before sending them (this encoding is 429 specified by the URI syntax [RFC3986]). 431 The user agent SHOULD inform the user about the possible security 432 hazards involved when submitting the form (it is probably being sent 433 as plain text over an air interface). 435 If the form submission is longer than the maximum SMS message size, 436 the user agent MAY either concatenate SMS messages, if it is able to 437 do so, or it MAY refuse to send the message. The user agent MUST NOT 438 send out partial form submissions. 440 2. URI Scheme Registration 442 This memo requests the registration of the Uniform Resource 443 Identifier (URI) scheme "sms" for specifying one or more recipients 444 for an SMS message. The registration request complies with RFC 4395 445 [RFC4395]. 447 2.1. URI Scheme Name 449 sms 451 2.2. Status 453 Provisional 455 2.3. URI Scheme Syntax 457 See Section 1.3. 459 2.4. URI Scheme Semantics 461 The "sms" defines a way how a message may be composed which is then 462 transmitted using the SMS message transmission method. This scheme 463 can thus be compared to be "mailto" URI scheme [RFC2368]. See 464 Section 1.3.3 for the details of operation. 466 2.5. Encoding Considerations 468 The optional body field of "sms" URIs may contain a message text, but 469 this text uses percent-encoded UTF-8 characters and thus can always 470 be represented using URI characters. See Section 1.3 for the details 471 of encoding. 473 2.6. Applications/Protocols that use this URI Scheme Name 475 The "sms" URI scheme is intended to be used in a similar way as the 476 "mailto" URI scheme [RFC2368]. By using "sms" URIs, authors can 477 embed information into documents which can be used as a starting 478 point for initiating message composition. Whether the client is 479 sending the message itself (for example over a GSM air interface) or 480 redirecting the user to a third party for message composition (such 481 as a Web service for sending SMS messages) is outside of the scope of 482 the URI scheme definition. 484 2.7. Interoperability Considerations 486 No interoperability issues have been identified. 488 2.8. Security Considerations 490 See Section 3. 492 2.9. Contact 494 Erik Wilde 495 School of Information 496 UC Berkeley 497 Berkeley, CA 94720-4600 498 U.S.A. 499 tel:+1-510-6432252 500 mailto:dret@berkeley.edu 502 3. Security Considerations 504 SMS messages are transported without any provisions for privacy or 505 integrity, so SMS users should be aware of these inherent security 506 problems of SMS messages. Unlike electronic mail, where additional 507 mechanisms exist to layer security features on top of the basic 508 infrastructure, there currently is no such framework for SMS 509 messages. 511 SMS messages very often are delivered almost instantaneously (if the 512 receiving SMS client is online), but there is no guarantee for when 513 SMS messages will be delivered. In particular, SMS messages between 514 different network operators sometimes take a long time to be 515 delivered (hours or even days) or are not delivered at all, so 516 applications SHOULD NOT make any assumptions about the reliability 517 and performance of SMS message transmission. 519 In most networks, sending SMS messages is not a free service. 520 Therefore, SMS clients MUST make sure that any action that incurs 521 costs is acknowledged by the end user, unless explicitly instructed 522 otherwise by the end user. If an SMS client has different ways of 523 submitting an SMS message (such as a Web service and a phone line), 524 then the end user MUST have a way to control which way is chosen. 526 SMS clients often are limited devices (typically mobile phones), and 527 the sending SMS client SHOULD NOT make any assumptions about the 528 receiving SMS client supporting any non-standard services, such as 529 proprietary message concatenation or proprietary content types. 530 However, if the sending SMS client has prior knowledge about the 531 receiving SMS client, then he MAY use this knowledge to compose non- 532 standard SMS messages. 534 There are certain special SMS messages defined in the SMS 535 specification [SMS] that can be used, for example, to turn on 536 indicators on the phone display, or to send data to certain 537 communication ports (comparable to UDP ports) on the device. Certain 538 proprietary systems (for example, the Wireless Application Protocol 539 [WAP]) define configuration messages that may be used to reconfigure 540 the devices remotely. Any SMS client SHOULD make sure that malicious 541 use of such messages is not possible, for example by filtering out 542 certain SMS User Data headers. Gateways that accept SMS messages 543 e.g. in e-mail messages or Web forms and pass them on to an SMSC, 544 SHOULD implement this kind of "firewalling" approach as well. 546 Because the narrow bandwidth of the SMS communications channel, there 547 should also be checks in place for excessively long concatenated 548 messages. As an example, it may take two minutes to transfer thirty 549 concatenated text messages. 551 Unchecked input from a user MUST NOT be used to populate any other 552 fields in a SMS message other than the User Data field (not including 553 the User Data Header field). All other parts, including the User 554 Data Header, of the short message should only be generated by trusted 555 means. 557 By including "sms" URIs in unsolicited messages (a.k.a. "spam") or 558 other types of advertising, the originator of the "sms" URIs may 559 attempt to reveal an individual's phone number and/or to link the 560 identity (i.e., e-mail address) used for messaging with the identity 561 (i.e., phone number) used for the mobile phone. This attempt to 562 collect information may be a privacy issue, and user agents may make 563 users aware of that risk before composing or sending SMS messages. 564 Users agents which do not provide any feedback about this privacy 565 issue make users more vulnerable to this kind of attack. 567 A user agent SHOULD NOT send out SMS messages without the knowledge 568 of the user, because of associated risks, which include sending 569 masses of SMS messages to a subscriber without his consent, and the 570 costs involved in sending an SMS message. 572 The user agent SHOULD have some mechanism that the user can use to 573 filter out unwanted destinations for SMS messages. The user agent 574 SHOULD also have some means of restricting the number of SMS messages 575 being sent as the result of activating one "sms" URI. 577 As suggested functionality, the user agent MAY offer a possibility 578 for the user to filter out those phone numbers that are expressed in 579 local format, as most premium-rate numbers are expressed in local 580 format, and because determining the correct local context (and hence 581 the validity of the number to this specific user) may be very 582 difficult. 584 When using "sms" URIs as targets of forms (as described in 585 Section 1.3.5), the user agent SHOULD inform the user about the 586 possible security hazards involved when submitting the form (it is 587 probably being sent as plain text over an air interface). 589 4. IANA Considerations 591 Upon publication of this memo as an RFC, IANA has registered the 592 "sms" URI scheme, using the template in Section 2, in accordance with 593 RFC 5234 [RFC5234]. 595 5. Change Log 597 This section will not be part of the final RFC text, it serves as a 598 container to collect the history of the individual draft versions. 599 Please remove this section before publication as RFC 601 5.1. From -14 to -15 603 o RFC 4234 (ABNF) has been obsoleted by [RFC5234]. 605 5.2. From -13 to -14 607 o Updated abstract of Section 2 to the new abstract of the complete 608 document (mentioning of gateway functionality removed). 610 o Removed the "smsc" qualifier which allowed the specification of an 611 SMSC to be used for SMS message delivery. 613 o Removed the section about interfacing between a user agent 614 processing an "sms" URI, and a Web-based service for SMS 615 composition and sending. 617 o Replaced "gstn-phone" with "sms-number" in Section 1.3.3 618 (inconsistency from earlier syntax revision). 620 o Replaced all quotes around ABNF symbols within text with <...> to 621 clearly identify them as ABNF. 623 o Updated all references to their complete XML version. 625 o Added Section 4. 627 5.3. From -12 to -13 629 o Updated [SMS] to point to the latest version of the SMS spec (3GPP 630 TS 23.040 V7.0.1). 632 o Removed support for telematic interworking from the draft. This 633 feature of SMS messaging is hard to understand, poorly supported 634 by clients as well as network operators, and for these reasons 635 would have been likely to see poor adoption in implementations 636 anyway. 638 o Added some text making it more clear that all recipients SHOULD be 639 sent the exact same message. 641 o Several small editorial changes. 643 5.4. From -11 to -12 645 o Integrated draft-wilde-sms-service-11 and 646 draft-wilde-sms-uri-registration-00 into this draft. This draft 647 is now self-contained. 649 o Changed the phone number notation to use the definition from RFC 650 3966 [RFC3966] rather than RFC 3601 (RFC 3966 is a simpler 651 notation disallowing some of the special characters allowed by RFC 652 3601). 654 o Rephrased various parts of Section 3. 656 o Removed Section "Author/Change Controller". 658 o RFC 2806 (tel URI scheme) has been obsoleted by [RFC3966]. 660 5.5. From -10 to -11 662 o RFC 2234 (ABNF) has been obsoleted by RFC4234. 664 o Updated reference information for [SMS] and [SMS-CHAR]. 666 o Minor textual changes. 668 5.6. From -09 to -10 670 o Added security consideration about filtering local format phone 671 numbers. 673 o Changed IPR clause from RFC 3667 to RFC 3978 (updated version of 674 RFC 3667). 676 5.7. From -08 to -09 678 o Fixed syntax error in hier-part and sms-recipient non-terminals, 679 which allowed sms-recipients to be concatenated without comma 680 separation. 682 5.8. From -07 to -08 684 o URIs are now defined by RFC 3986 [RFC3986], so the text (including 685 the syntax definitions) and the references have been updated. 687 5.9. From -06 to -07 689 o Changed IPR clause from RFC 2026 to RFC 3667 (updated version of 690 RFC 2026). 692 5.10. From -05 to -06 694 o Updated reference from draft-allocchio-gstn to RFC 3601. 696 5.11. From -04 to -05 698 o Updated reference to SMS spec to the version referenced in the SMS 699 service draft. 701 5.12. From -03 to -04 703 o Updated reference to draft-allocchio-gstn (to revision -05). 705 5.13. From -02 to -03 707 o Changed ordering of "change Log" section (descending to 708 ascending). 710 o Clarified the wording at the beginning of Section 1.3.2 about only 711 the keywords of the scheme being case-insensitive. 713 o Changed "sms-body" to be a URI query string. 715 o Added some text describing "sms" URIs as addressing resources. 717 5.14. From -01 to -02 719 o Changed the sms-body field to percent-encoded UTF-8 characters. 721 5.15. From -00 to -01 723 o Added the "sms-body" field and its processing rules. 725 o Added section about using "sms" URIs as query strings for SMS Web 726 services. 728 o Fixed typo in ABNF (said "global-phone" instead of "gstn-phone"). 730 o Added some explanatory text about form submissions using email 731 telematic interworking. 733 o Added some text about character encoding in form submissions. 735 5.16. Change Log of draft-wilde-sms-service 737 This section contains the change log of draft-wilde-sms-service-11 738 before it was incorporated into this document at version 739 draft-wilde-sms-uri-12. 741 5.16.1. From -10 to -11 743 o RFC 2234 (ABNF) has been obsoleted by RFC4234. 745 o Added new security issue in Section 3. 747 o Updated reference information for [SMS] and [SMS-CHAR]. 749 o Minor textual changes. 751 5.16.2. From -09 to -10 753 o Changed IPR clause from RFC 3667 to RFC 3978 (updated version of 754 RFC 3667). 756 5.16.3. From -08 to -09 758 o No changes, re-release for alignment with draft-wilde-sms-uri. 760 5.16.4. From -07 to -08 762 o No changes, re-release for alignment with draft-wilde-sms-uri. 764 5.16.5. From -06 to -07 766 o Changed IPR clause from RFC 2026 to RFC 3667 (updated version of 767 RFC 2026). 769 5.16.6. From -05 to -06 771 o Updated reference from draft-allocchio-gstn-05 to RFC 3601. 773 5.16.7. From -04 to -05 775 o No changes, re-release for alignment with draft-wilde-sms-uri. 777 5.16.8. From -03 to -04 779 o Updated reference to draft-allocchio-gstn (to revision -05). 781 5.16.9. From -02 to -03 783 o Changed ordering of "change Log" section (descending to 784 ascending). 786 o Fixed some spelling errors. 788 5.16.10. From -01 to -02 790 o Removed address specification for X.400 SMS from ABNF 791 (surprisingly not part of the SMS spec). 793 o Added some explanatory text about character set mapping for SMS 794 messages. 796 o Added text requiring the use of message class 1 for sending SMS 797 messages. 799 5.16.11. From -00 to -01 801 o Added a number of new security considerations. 803 o Added the "PID" qualif-type1 keyword and the section about "SMS 804 Telematic Interworking" (removed in -13, available as Section 805 1.2.3 in -12). 807 6. References 809 6.1. Normative References 811 [HTML401] Raggett, D., Le Hors, A., and I. Jacobs, "HTML 4.01 812 Specification", W3C REC-html401, December 1999, 813 . 815 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 816 Requirement Levels", BCP 14, RFC 2119, March 1997. 818 [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, 819 April 2001. 821 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 822 10646", STD 63, RFC 3629, November 2003. 824 [RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers", 825 RFC 3966, December 2004. 827 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 828 Resource Identifier (URI): Generic Syntax", STD 66, 829 RFC 3986, January 2005. 831 [RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and 832 Registration Procedures for New URI Schemes", BCP 115, 833 RFC 4395, February 2006. 835 [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 836 Specifications: ABNF", RFC 5234, January 2008. 838 [SMS] European Telecommunications Standards Institute, "3GPP TS 839 23.040 V7.0.1 (2007-03): 3rd Generation Partnership 840 Project; Technical Specification Group Core Network and 841 Terminals; Technical realization of the Short Message 842 Service (SMS) (Release 7)", March 2007, . 846 [SMS-CHAR] 847 European Telecommunications Standards Institute, "TS 100 848 900 (GSM 03.38 version 7.2.0 Release 1998): Digital 849 Cellular Telecommunications System (Phase 2+); Alphabets 850 and language-specific information", July 1999, . 854 6.2. Non-Normative References 856 [RFC2368] Hoffmann, P., Masinter, L., and J. Zawinski, "The mailto 857 URL scheme", RFC 2368, June 1998. 859 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, 860 June 1999. 862 [RFC2838] Zigmond, D. and M. Vickers, "Uniform Resource Identifiers 863 for Television Broadcasts", RFC 2838, May 2000. 865 [WAP] WAP Forum, "Wireless Application Protocol - Architecture 866 Specification (WAP-210-WAPArch-20010712)", July 2001. 868 [uri-clarification] 869 World Wide Web Consortium, "URIs, URLs, and URNs: 870 Clarifications and Recommendations 1.0", W3C uri- 871 clarification , September 2001, 872 . 874 Appendix A. Where to send Comments 876 Please send all comments and questions concerning this document to 877 Erik Wilde. 879 Appendix B. Acknowledgements 881 This document has been prepared using the IETF document DTD described 882 in RFC 2629 [RFC2629]. 884 Thanks to Claudio Allocchio, Lisa Dusseault, Larry Masinter, Alfred 885 Hoenes, Graham Klyne, Derek Atkins, Michael Patton, and Vijay Gurbani 886 for their comments. 888 Authors' Addresses 890 Erik Wilde 891 UC Berkeley 892 Berkeley, CA 94720-4600 893 U.S.A. 895 Phone: +1-510-6432253 896 Email: dret@berkeley.edu 897 URI: http://dret.net/netdret/ 899 Antti Vaha-Sipila 900 Nokia 902 Email: antti.vaha-sipila@nokia.com 903 URI: http://www.iki.fi/avs/ 905 Full Copyright Statement 907 Copyright (C) The IETF Trust (2008). 909 This document is subject to the rights, licenses and restrictions 910 contained in BCP 78, and except as set forth therein, the authors 911 retain all their rights. 913 This document and the information contained herein are provided on an 914 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 915 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 916 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 917 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 918 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 919 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 921 Intellectual Property 923 The IETF takes no position regarding the validity or scope of any 924 Intellectual Property Rights or other rights that might be claimed to 925 pertain to the implementation or use of the technology described in 926 this document or the extent to which any license under such rights 927 might or might not be available; nor does it represent that it has 928 made any independent effort to identify any such rights. 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