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From: pyuxp!towernet!rigel!tiprvt@bellcore.bellcore.com
Newsgroups: comp.dcom.telecom
Subject: Re: Caller-ID Theory and Operation
Message-ID: <8773@accuvax.nwu.edu>
Date: 7 Jun 90 10:35:53 GMT
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X-Telecom-Digest: Volume 10, Issue 419, Message 9 of 11


Caller ID, or whatever the local telephone company calls it, is not
specifically a part of ISDN, although ISDN has the same functionality
it works differently.  Caller ID is accomplished by transmitting the
calling number in FSK format between the first and second rings.  If
you pick up on the first ring, the calling number often is lost and
will not display.

My "box" is about 5 by 3 by 1/2 inches, flat, with a LCD display and
cost in the low $60 range.  It stores about 60 calls, I think, and
dates and time stamps the calls.  There are three buttons on the
display, scroll forward, scroll back, and delete number.

I don't know of any reason you could not use a modem and pc to display
the numbers, perhaps associating them with real names.  I've heard
units with RS-232 output are available.

The specification for this service has been published by Bellcore for
vendors to use.  I've never seen the documents, but they probably have
a lot of technical information.

I find Caller ID to be useful, but until it is more widely deployed,
it will have limitations.  For interoffice or interstate use,
Signalling System 7 is required to pass the number outside the call
path.  Another problem is political, the Pennsylvania courts have
found this the same as wire taps (I don't agree) and there are strong
opinions on both sides of the issue as to whose privacy is invaded.


Roger V. Thompson, P.E. (tiprvt@rigel.cc.bellcore.com) (201)
758-2875 (Office) (201) 747-7213 (Home) ARS AD5T 1184 Ocean Ave. D-1,
Sea Bright, NJ ) 07760