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From: dave@westmark.westmark.com (Dave Levenson)
Newsgroups: comp.dcom.telecom
Subject: Re: Caller-ID Technical Question
Message-ID: <74451@bu.edu.bu.edu>
Date: 11 Feb 91 03:22:00 GMT
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X-Telecom-Digest: Volume 11, Issue 110, Message 8 of 8


In article <74363@bu.edu.bu.edu>, larson@snmp.sri.com (Alan Larson)
writes:

>   As I understand it, Caller-ID works by sending the information out
> after the first or second ring.  Why doesn't it send it out before the
> first ring, so the phone could know if it was to ring at all.

The Caller*ID display devices I have seen use the first ring to turn
on the detector, and then sense the data carrier.  Data preceding the
first ring would not be noticed by these devices.

One could certainly build a device that intercepts the first ring, and
doesn't pass it through to the telephone instrument until it has
received and processed the Caller*ID transmission.  I have not seen
such a device on the market yet, however.


Dave Levenson		Internet: dave@westmark.com
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