Caller ID

Mike O'Dell mo at
Tue Oct 2 07:32:39 CDT 2007

Paul L Rinaldo wrote:
> Gang,
> If one received a caller ID of 122 ­ 752- 2327, being that 122 doesn't 
> look like an area code, what does it signify?
> Paul
> ------------------------------------------------------------------------
> _______________________________________________
> Tacos mailing list
> Tacos at

indeed, there are no area-codes beginning with "1"

however, with ISDN PRI service, typically connected
to a PBX or other call center hardware, one can completely
specify the digit string the recipient sees as "caller-ID".
(I don't remember whether this works with BRI ISDN service.)

hence, there's an extremely good chance this is a junk call.

if there is a digit missing after 122, then it could be
a dial-string since the leading "1" is the country-code,
and most people have to dial the leading "1" these days.
this is somewhat odd because most people also have to
dial the "011" international access code so that the
remainder of the digit string is interpreted in full
E.164 glory. (country-code followed by country-specific stuff)

one thing i didn't understand until i worked at Bellcore
is that the *dialing plan* is distinct from the *numbering plan*.
the dialing plan defines an encoding and the number plan defines
the strings generated by the dialing-plan encodings.
this is not at all obvious from a casual inspection, nor from
a historical understanding of how phone numbers have evolved
from being genuine "addresses" (in the computer-science sense)
into "names" able to support arbitrary mappings and meaningless
without the computer database supplying those mappings.


ps - Unabashed plug for a good friend's new book:

i've been aiding and abetting John's work for several years now
and this book is going to be a real whack up the side of the head for many.
i mention this because it contains the best (if not only) complete
analysis of addressing in computer networks and the semantic properties
required of the "addresses" at each level in the architecture.
this reveals precisely why IPv6 is not only not better than IPv4,
but demonstrably worsens already intractable problems with IPv4.

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