1. Introduction

   There is currently a need for a mechanism to identify the originating
   party of a voice mail message, outside of the "FROM" header
   information.  The telephone number and name of the caller are
   typically available from the telephone network, but there is no
   obvious header field to store this in an Internet Mail message.

   This information is intended for use when the VPIM message format is
   used for storing "Call Answer" voice messages in an Internet Mail
   message store, i.e., the calling party leaves a voice message for the
   recipient, who was unable to answer the call.  The implication is
   that there is no RFC 2822prop address known for the originator.

   [VPIMV2R2] suggests the originating number be included as an Internet
   address, using the first method shown below.  There are several other
   ways to store this information, but they all involve some
   manipulation of the "From" field.  For example:

      1. From: "416 555 1234" <non-mail-user@host>
      2. From: "John Doe" <4165551234@host>
      3. From:  unknown:;

   Since any of these is a forced translation, it would be useful to
   store the calling party's name and number as presented by the
   telephone system to the called party without manipulation.  This
   would allow the calling party's information to be displayed to the
   recipient (similar to it appearing on the telephone) and also allow
   future determination of an Internet address for the originator (if
   one exists).  Note that there is no requirement to store meta-data
   (e.g., type of number, presentation restricted), as this information
   is not presented to the called party and is generally not available
   to voice mail systems.  The intent is to store the available
   information to an analog (non-ISDN) phone (e.g., per [T1.401] in
   North America).

   [RFC2076] currently lists "phone" as an Internet message header which
   would hold the originating party's telephone number, but it is listed
   as "non-standard", i.e., usage of this header is not generally
   recommended.  It also has no defined format, making the information
   unparsable.  There is no similar entry for the originator's name.

   It is proposed that two new message header fields be included to hold
   this information, namely the Calling Line Identification ("Caller-
   ID") and Caller Name ("Caller-Name").