wmartin@ALMSA-1.ARPA.UUCP (03/31/87)
A few more telecom-related postings from RISKS 4.68:
Will Martin
Date: Wed, 25 Mar 87 15:08:58 PST
From: Andrew Klossner <andrew%lemming.gwd.tek.com@RELAY.CS.NET>
To: risks@CSL.SRI.COM
Subject: Re: Increased Telephone Switching Capabilities
This topic was discussed at length in the TELECOM list. Some items ...
"I discussed this article with a friend, who [asserted that]
the information (calling #) is already available, and is
encoded somehow just prior to the ring spike on the receiving line."
There is no truth to this statement. Under normal circumstances, when
the originating and receiving exchanges (CO's) are different, the
receiving exchange has no way of knowing the origination number.
"I don't see any obvious risks to the new features."
On of my concerns is that, with these features, I can no longer keep my
unlisted phone number private. If I call a local department store to
get their price on a pair of shoes, I may start getting unsolicited
shoe sales calls from all over. Merchants would be motivated to
collect and sell lists of phone numbers of consumers with particular
interests, just as they now collect and sell mailing addresses. (And I
can't make use of that "call screening" feature; what if my daughter is
in trouble and tries to call home from a phone booth?)
MORE: Re: Michael Wagner (RISKS-4.67)
"1) the 911 emergency number in Toronto displays the number
from which a call was made...
An originating exchange sends the information only when it's using the
special 911 subsystem. (At my exchange this goes out on a special
trunk directly to the 911 center, it doesn't travel between exchanges.)
The implications don't follow.
"2) The University of Toronto recently switched over to a Centrex III
system. Certain (secretarial) phones can now display the number called and
the number calling. The number calling works only if the call originated
within the centrex exchange. It is not clear whether the restriction is
technical or legal...
It's technical, that's the Centrex system talking to itself.
-=- Andrew Klossner (decvax!tektronix!tekecs!andrew) [UUCP]
(tekecs!andrew.tektronix@csnet-relay) [ARPA]
------------------------------
Date: Wed 25 Mar 87 11:19:30-EST
From: LINDSAY@TL-20B.ARPA
Subject: Re: phone number of caller
To: risks@CSL.SRI.COM
At first glance, it seems simple to be told where your caller is calling from.
All that one needs is a small display: after all, exchanges are computerized
now, aren't they ?
Well, yes, new ones are. Also, new exchanges tend to be bigger: several
exchange numbers are implemented by a single office, rather than being
one-for-one. And, of course, if all the action occurs within a single
exchange, then the features that are offered are just a Small Matter Of
Programming.
However, old phone exchanges are still with us. Projected reliability
used to be stated as outage-time per forty years ! Also, old designs
were being built until recently. For example, Bermuda bought a mechanical
stepping exchange (from Philips) in the early 1970's.
When authorities try to trace phone calls, the major stumbling block is
usually that the call has crossed one or more boundaries between exchanges.
Tracing then becomes a serial process, and it used to involve a human
at each physical location. A person wishing to (say) utter death threats
was quite difficult to catch, particularly if rural equipment was in the chain.
Of course, we will eventually resolve these problems. Mad bombers will
respond by using pay phones, unattended autodialers, and other tactics.
Don Lindsay
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From: rochester!kodak!grodberg@seismo.CSS.GOV (jeremy grodberg)
Date: 26 Mar 87 22:58:38 GMT
To: mod-risks@seismo.CSS.GOV
Subject: Who called? (Re: RISKS DIGEST 4.66 and 4.67)
Date: 26 Mar 87 22:58:37 GMT
According to _High Technology_, a caller placing a call from an unlisted
phone can prevent the number from being displayed on the destination phone
by entering a code. The phone company equipment still gets the number
though, so the person being called can call still call the person with the
unlisted phone number (using a feature which dials the number of the most
recent incoming call), although there is no (legitimate) way to actually
determine the unlisted number.
Jeremy Grodberg
------------------------------
Date: Wed, 25 Mar 87 09:24:37 pst
From: dual!paul@ucbvax.Berkeley.EDU (Paul Wilcox-Baker)
To: ucbvax!CSL.SRI.COM!RISKS
Subject: Hang-ups [Re: RISKS-4.67]
> As far as I know it depends on the "office" (telephone company term for
> switching equipment) connected to your phone... An electronic office will
> close the connection as soon as either party hangs up.
Actually, this is not true. For most electronic exchanges in the U.S., the
connection is held until about 20 seconds after the called party hangs up, or
whenever the calling party hangs up. This is supposed to let the answering
party hang up one phone, move to a different room and continue using another.
The timeout is reset every time the phone goes off-hook. This causes the
apparent inability to get rid of the incoming call. The best solution to
obnoxious electronic calling machines is legal - ban the damn things!
Paul Wilcox-Baker.
******
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