Dave Crocker (dcrocker@brandenburg.com)
Sat, 23 Jun 2001 10:10:56 -0700
Folks,
Concerning: <draft-ema-vpim-clid-02.txt>
This I-D attempts to provide an extremely useful increment to Internet
Mail, namely the encoding of GSTN information about the caller who
originated a voicemail.
Current VPIM approaches for achieving this functionality suffer from
ambiguity and/or excessive specialization. That is, a proposed convention
does not adequately distinguish the information or it uses techniques that
make a VPIM practise distinct from usual Internet mail practise.
Specifically:
1. Creation of special headers for addressing is entirely outside normal
Internet mail architectural style. It typically creates correlation
problems, between the usual set of addressing headers and the new
set. Additional headers also often are dropped by gateways.
2. Telephone number encoding in local-part, per the main VPIM
specification, does not label the information well enough to distinguish
it from a random system mailbox string or random email system encoding
convention.
3. The current I-D also permits use of partial telephone numbering
strings, when originator and recipient share the same telephone
"domain". This technique ensures that telephone information in forwarded
messages cannot be used outside of the local domain. It is the reason that
Internet mail and domain name specifications always call for the full,
global string.
Happily, it looks as if remedying these problems is reasonably
straightforward...
All of the information about the caller needs to be put into the From
field. Put information about the voicemail system that is doing the work
into the Sender field. (The sender field was created for representing the
mediating agent of the originator.)
If the name of the originator is known, then put it into the display
string, as is usual for Internet Mail. Define a standard string to use if
the originator is unknown, such as... "UNKNOWN", or just leave that field
blank, as is usual for Internet Mail.
There are two choices for encoding the caller's phone number. One uses
ENUM -- domain name encoding -- and the other uses the technique described
in RFC 2303, "Minimal PSTN address format in Internet Mail".
ENUM really is intended for infrastructure telephone switching
services. Because the phone number is in reverse order, it is difficult
for humans to read. Its use also would require creating a 'standard'
mailbox name, to fill in the local-part of the address.
Hence I recommend RFC2303 format. This format also permits encoding
additional parametric information, such as the t1.401 field cited in the I-D:
The RFC2303 style would be along the lines of:
From: VOICE=+14082468253@vpim-gateway.net
From: Dave Crocker <VOICE=+14082468253@vpim-gateway.net>
From: Dave Crocker <VOICE=+14082468253/t1401=date@vpim-gateway.net>
d/
----------
Dave Crocker <mailto:dcrocker@brandenburg.com>
Brandenburg InternetWorking <http://www.brandenburg.com>
tel: +1.408.246.8253; fax: +1.408.273.6464
This archive was generated by hypermail 2.0b3 on Sat Jun 23 2001 - 20:09:17 IDT