Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!ames!think!eplunix!raoul
From: raoul@eplunix.UUCP (Otero)
Newsgroups: sci.electronics
Subject: Re: Information about Answering Machine
Summary: Displaying Incoming Phone Numbers
Message-ID: <693@eplunix.UUCP>
Date: 16 Mar 89 19:58:32 GMT
References: <1467@PSUECLB> <251@poppy.warwick.ac.uk>
Organization: Eaton-Peabody Lab, Boston, MA
Lines: 22


In article <1467@PSUECLB> was@psueclb.BITNET writes:
>    I have interest to buy an answering machine which has the
>capability to display the incoming telephone number before I pick
>up the phone receiver.

There has been a debate in the New England area on whether to provide
this service as part of a package. Yes, it's called tracing the call.
On an old switching relay system, it's not trivial: Fike and Friend's
"Undestanding Telephone Electronics" goes into some detail on the
system. On the new computer switching systems, since there is some
memory that remembers what phones are hooked to what bus lines,
transmitting the number of the caller would be trivial with a well
designed system. The problem is for confidential recipients, like
suicide lines, and unlisted callers. Do you *really* want the
suicide hotline to have your number if you call? Or to give
out your unlisted number every time you call for pizza?

-- 
			Nico Garcia, Engineer, CIRL 
			Mass. Eye and Ear Hospital
			raoul@eplunix