URI Scheme for Global System for Mobile Communications (GSM) Short Message Service (SMS)
RFC 5724

quot; URI Scheme                 January 2010

   collect information may be a privacy issue, and user agents may make
   users aware of that risk before composing or sending SMS messages.
   Users agents that do not provide any feedback about this privacy
   issue make users more vulnerable to this kind of attack.

   A user agent SHOULD NOT send out SMS messages without the knowledge
   of the user because of associated risks, which include sending masses
   of SMS messages to a subscriber without his consent, and the costs
   involved in sending an SMS message.

   As suggested functionality, the user agent MAY offer a possibility
   for the user to filter out those phone numbers that are expressed in
   local format, as most premium-rate numbers are expressed in local
   format, and because determining the correct local context (and hence
   the validity of the number to this specific user) may be very
   difficult.

   When using "sms" URIs as targets of forms (as described in
   Section 2.6), the user agent SHOULD inform the user about the
   possible security hazards involved when submitting the form (it is
   probably being sent as plain text over an air interface).

5.  IANA Considerations

   IANA has registered the "sms" URI scheme, using the template in
   Section 3, in accordance with [RFC4395].

6.  Acknowledgements

   This document has been prepared using the IETF document DTD described
   in [RFC2629].

   Thanks to (listed alphabetically) Claudio Allocchio, Derek Atkins,
   Nevil Brownlee, John Cowan, Leslie Daigle, Lisa Dusseault, Miguel
   Garcia, Vijay Gurbani, Alfred Hoenes, Cullen Jennings, Graham Klyne,
   Larry Masinter, Alexey Melnikov, Michael Patton, Robert Sparks, and
   Magnus Westerlund for their comments.

7.  References

7.1.  Normative References

   [Err203]   RFC Errata, "Errata ID 203", RFC 3629,
              <http://www.rfc-editor.org>.

   [HTML401]  Raggett, D., Le Hors, A., and I. Jacobs, "HTML 4.01
              Specification", W3C REC-html401, December 1999,
              <http://www.w3.org/TR/html401/>.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC3966]  Schulzrinne, H., "The tel URI for Telephone Numbers",
              RFC 3966, December 2004.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 35,
              RFC 4395, February 2006.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [SMS]      European Telecommunications Standards Institute, "3GPP TS
              23.040 V7.0.1 (2007-03): 3rd Generation Partnership
              Project; Technical Specification Group Core Network and
              Terminals; Technical realization of the Short Message
              Service (SMS) (Release 7)", March 2007, <http://
              www.3gpp.org/ftp/Specs/archive/23_series/23.040/
              23040-701.zip>.

   [SMS-CHAR]
              European Telecommunications Standards Institute, "TS 100
              900 (GSM 03.38 version 7.2.0 Release 1998): Digital
              Cellular Telecommunications System (Phase 2+); Alphabets
              and language-specific information", July 1999, <http://
              www.3gpp.org/ftp/Specs/archive/03_series/03.38/
              0338-720.zip>.

7.2.  Informative References

   [RFC2368]  Hoffmann, P., Masinter, L., and J. Zawinski, "The mailto
              URL scheme", RFC 2368, June 1998.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC2838]  Zigmond, D. and M. Vickers, "Uniform Resource Identifiers
              for Television Broadcasts", RFC 2838, May 2000.

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   [WAP]      WAP Forum, "Wireless Application Protocol - Architecture
              Specification (WAP-210-WAPArch-20010712)", July 2001.

   [uri-clarification]
              World Wide Web Consortium, "URIs, URLs, and URNs:
              Clarifications and Recommendations 1.0", W3C uri-
              clarification , September 2001,
              <http://www.w3.org/TR/uri-clarification/>.

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Appendix A.  Syntax of 'telephone-subscriber'

   The following syntax is reproduced from Section 3 of [RFC3966].  It
   defines the <telephone-subscriber> part used in the "sms" URI scheme
   syntax.  Please note that it includes Erratum 203 [Err203] for RFC
   3966, which changes the definition of <isdn-subaddress>.

   telephone-subscriber = global-number / local-number
   global-number        = global-number-digits *par
   local-number         = local-number-digits *par context *par
   par                  = parameter / extension / isdn-subaddress
   isdn-subaddress      = ";isub=" 1*paramchar
   extension            = ";ext=" 1*phonedigit
   context              = ";phone-context=" descriptor
   descriptor           = domainname / global-number-digits
   global-number-digits = "+" *phonedigit DIGIT *phonedigit
   local-number-digits  =
      *phonedigit-hex (HEXDIG / "*" / "#")*phonedigit-hex
   domainname           = *( domainlabel "." ) toplabel [ "." ]
   domainlabel          = alphanum
                          / alphanum *( alphanum / "-" ) alphanum
   toplabel             = ALPHA / ALPHA *( alphanum / "-" ) alphanum
   parameter            = ";" pname ["=" pvalue ]
   pname                = 1*( alphanum / "-" )
   pvalue               = 1*paramchar
   paramchar            = param-unreserved / unreserved / pct-encoded
   unreserved           = alphanum / mark
   mark                 = "-" / "_" / "." / "!" / "~" / "*" /
                          "'" / "(" / ")"
   pct-encoded          = "%" HEXDIG HEXDIG
   param-unreserved     = "[" / "]" / "/" / ":" / "&" / "+" / "$"
   phonedigit           = DIGIT / [ visual-separator ]
   phonedigit-hex       = HEXDIG / "*" / "#" / [ visual-separator ]
   visual-separator     = "-" / "." / "(" / ")"
   alphanum             = ALPHA / DIGIT

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Authors' Addresses

   Erik Wilde
   UC Berkeley
   School of Information
   Berkeley, CA 94720-4600
   U.S.A.

   Phone: +1-510-6432253
   EMail: dret@berkeley.edu
   URI:   http://dret.net/netdret/

   Antti Vaha-Sipila
   Nokia

   EMail: antti.vaha-sipila@nokia.com
   URI:   http://www.iki.fi/avs/

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