rfc1703.txt

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Network Working Group                                            M. Rose
Request for Comments: 1703                  Dover Beach Consulting, Inc.
Obsoletes: 1569                                             October 1994
Category: Informational


           Principles of Operation for the TPC.INT Subdomain:
                  Radio Paging -- Technical Procedures

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Table of Contents

   1. Introduction ...............................................    1
   2. Naming, Addressing, and Routing ............................    2
   2.1 Addressing ................................................    2
   2.2 Routing ...................................................    3
   3. Procedure ..................................................    3
   3.1 Alpha-numeric Radio Pagers ................................    3
   3.2 Numeric Radio Pagers ......................................    4
   3.3 MAILing versus SENDing ....................................    4
   3.4 Latency ...................................................    5
   4. Usage Examples .............................................    5
   4.1 A MIME Example ............................................    6
   4.2 A Non-MIME Example ........................................    6
   5. Server Configuration Example ...............................    6
   6. Security Considerations ....................................    8
   7. Acknowledgements ...........................................    8
   8. References .................................................    8
   9. Author's Address ...........................................    9

1.  Introduction

   As an adjunct to the usual, two-way electronic mail service, it is at
   times useful to employ a one-way text notification service, called
   radio paging.  This memo describes a technique for radio paging using
   the Internet mail infrastructure.  In particular, this memo focuses
   on the case in which radio pagers are identified via the
   international telephone network.

   The technique described by this memo, mapping telephone numbers to
   domain names, is derived from the TPC.INT subdomain.  Consult RFC
   1530, "Principles of Operation for the TPC.INT Subdomain: General
   Principles and Policy" for overview information.



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RFC 1703          Radio Paging -- Technical Procedures      October 1994


2.  Naming, Addressing, and Routing

   A radio pager is identified by a telephone number, e.g.,

     [phone]

   where "+1" indicates the IDDD country code, and the remaining string
   is a telephone number within that country.

   In addition to a telephone number, a PIN may also be required to
   uniquely identify a radio pager.

2.1.  Addressing

   This number is used to construct the address of a radio paging
   server, which forms the recipient address for the message, e.g., one
   of:

     pager.ATOM@6.7.7.8.0.4.9.5.1.4.1.tpc.int
     pager-alpha.ATOM@6.7.7.8.0.4.9.5.1.4.1.tpc.int
     pager-numeric@6.7.7.8.0.4.9.5.1.4.1.tpc.int

   where "ATOM" is an RFC 822 atom [1], an opaque string for use in
   recipient identification when communicating with the paging network,
   and the domain-part is constructed by reversing the telephone number,
   converting each digit to a domain-label, and being placed under
   "tpc.int".  (The telephone number must not include any international
   access codes.)

   Note that the mailbox syntax is purposefully restricted in the
   interests of pragmatism.  To paraphrase STD 11, RFC 822, an atom is
   defined as:

     atom    = 1*atomchar

     atomchar=   <any upper or lowercase alphabetic character
                  (A-Z a-z)>
               / <any digit (0-9)>
               / "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+"
               / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{"
               / "|" / "}" / "~"

   Finally, note that some Internet mail software (especially gateways
   from outside the Internet) impose stringent limitations on the size
   of a mailbox-string.  Thus, originating user agents should take care
   in limiting the local-part to no more than 70 or so characters.





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RFC 1703          Radio Paging -- Technical Procedures      October 1994


2.2.  Routing

   The message is routed in exactly the same fashion as all other
   electronic mail, i.e., using the MX algorithm [2].  Since a radio
   paging server might be able to access many radio pagers, the
   wildcarding facilities of the DNS [3,4] are used accordingly.  For
   example, if a radio paging server residing at "dbc.mtview.ca.us" is
   willing to access any radio pager with a telephone number prefix of

     +1 415 940

   then this resource record might be present

     *.0.4.9.5.1.4.1.tpc.int.       IN MX 10 dbc.mtview.ca.us.

   Naturally, if several radio paging servers were willing to access any
   radio pager in that prefix, multiple MX resource records would be
   present.  (The DNS servers for the TPC.INT subdomain perform a
   rudimentary form of load balancing by rotating the order of the MX
   records returned on each query.)

   It should be noted that the presence of a wildcard RR which matches a
   radio paging server's address does not imply that the corresponding
   telephone number is valid, or, if valid, that a radio pager is
   identified by the phone number.  Rather, the presence of a wildcard
   RR indicates that a radio paging server is willing to attempt access.

3.  Procedure

   When information is to be sent to a radio pager, the user application
   constructs an RFC 822 message, containing a "Message-ID" field and a
   textual content (e.g., a "text/plain" content [5]).

   The message is then sent to the radio paging server's electronic mail
   address.  The radio paging server begins by looking at the local part
   of the address.

3.1.  Alpha-numeric Radio Pagers

   If the local-part is either "pager.ATOM" or "pager-alpha.ATOM" then
   this indicates that the recipient is using an alpha-numeric radio
   pager, and ATOM either identifies a paging network (CARRIER), or a
   radio pager identity number (PIN), or both, according to these rules:

   (1)  if ATOM consists entirely of numeric characters, then ATOM is a
        PIN, and the domain-part refers to the IXO access telephone
        number for a radio paging carrier; otherwise,




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RFC 1703          Radio Paging -- Technical Procedures      October 1994


   (2)  if ATOM does not contain a hyphen character ("-"), then ATOM is
        a CARRIER, a local database is consulted to determine the
        corresponding IXO access telephone number, and the telephone
        number corresponding to the domain-part is used to identify the
        radio pager; otherwise,

   (3)  if ATOM does contain a hyphen character ("-"), then everything
        to the left of the first hyphen is a CARRIER, and everything to
        the right of that hyphen is a PIN, a local database is consulted
        to determine the corresponding IXO access telephone number, and
        the PIN is used is used to identify the radio pager.

   If the local-part starts with "pager.", then the message sent to the
   radio pager consists of the body of the message; otherwise, if the
   local-part starts with "pager-alpha.", then the radio paging server
   determines which information in the headers and body of the message
   are used when constructing the paging message.  For example, some
   radio paging servers might choose to examine the "To" and "Subject"
   fields, in addition to the body, whilst other radio paging servers
   might choose to simply send the body verbatim.

3.2.  Numeric Radio Pagers

   If the local-part is the literal string "pager-numeric" then this
   indicates that the recipient is using a numeric pager, and the radio
   pager dials the telephone number corresponding to the domain-part.

   The message sent to the radio pager consists of the body of the
   message, which must consist solely of digits.

3.3.  MAILing versus SENDing

   An SMTP client communicating with a radio paging server may use
   attempt either the MAIL or SEND command.  The radio paging server
   MUST support the MAIL command, and MAY support any of the SEND, SOML,
   or SAML commands.

   If the MAIL command is used, then a positive completion reply to both
   the RCPT and DATA commands indicates, at a minimum, that the message
   has been queued for transmission into the radio paging network for
   the recipient, but is at least queued for transmission into the radio
   paging network.

   If the SEND command is used, then a positive completion reply to both
   the RCPT and DATA commands indicates that the message has been
   accepted by the radio paging network for delivery to the recipient.





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RFC 1703          Radio Paging -- Technical Procedures      October 1994


   If the SOML or SAML command is used, then a positive completion reply
   to both the RCPT and DATA commands indicates that the message may
   have been accepted by the radio paging network for delivery to the
   recipient.

3.4.  Latency

   Although the Internet electronic mail service tends to perform
   delivery in a timely and reliable manner, some paging services will
   wish to provide a higher degree of assurance to their clients, in
   particular guaranteeing that a positive reply code means that the
   page has been sent on the radio paging network.  For such
   requirements, the primary constraints are server implementation and
   client/server network connectivity.

   A client that uses the SEND or SAML commands is explicitly requesting
   real-time transmission on the radio paging network and is requiring
   that the server reply code will carry a statement of success or
   failure about that transmission.

   The IP level of the Internet performs datagram store-and-forward
   service, but gives the end system hosts the appearance of direct
   connectivity, by virtue of allowing interactive service.  The
   Internet electronic mail service adds another layer of store-and-