RFC 2303 (rfc2303) - Page 2 of 8

Minimal PSTN address format in Internet Mail

RFC 2303             Minimal PSTN in Internet Mail            March 1998


   This memo describes the MINIMAL addressing method to encode PSTN
   addresses into e-mail addresses and the standard extension mechanism
   to allow definition of further standard elements. The opposite
   problem, i.e. to allow a traditional numeric-only PSTN device user to
   access the e-mail transport service, is not discussed here.

   All implementations supporting this PSTN over e-mail service MUST
   support as a minimum the specification described in this document.
   The generic complex case of converting the whole PSTN addressing into
   e-mail is out of scope in this minimal specification: there is some
   work in progress in the field, where also a number of standard
   optional extensions are being defined.

   In this document the formal definitions are described using ABNF
   syntax, as defined into [7]. We will also use some of the "CORE
   DEFINITIONS" defined in "APPENDIX A - CORE" of that document. The
   exact meaning of the capitalised words

      "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
      "SHOULD NOT", "RECOMMENDED",  "MAY", "OPTIONAL"

   is defined in reference [6].

2. Minimal PSTN address

   The minimal specification of a PSTN address in e-mail address is as
   follows:

      pstn-address = pstn-mbox  [ qualif-type1 ]

      pstn-mbox = service-selector "=" global-phone

      service-selector = 1*( DIGIT / ALPHA / "-" )
                         ; note that SP (space) is not allowed in
                         ; service-selector.
                         ; service-selector MUST be handled as a case
                         ; INSENSITIVE string by implementations.

   Specifications adopting the "pstn-address" definition MUST define a
   unique case insensitive "service-selector" element to identify the
   specific messaging service involved.

   These specifications MUST also define which minimal "qualif-type1"
   extensions, if any, MUST be supported for the specified service.

   Implementations confirming to these minimal requirements
   specification are allowed to ingnore any other non-minimal extensions
   address element which can be present in the "pstn-address". However,



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