The Risks Digest

The RISKS Digest

Forum on Risks to the Public in Computers and Related Systems

ACM Committee on Computers and Public Policy, Peter G. Neumann, moderator

Volume 9 Issue 84

Thursday 26 April 1990


o Re: You think YOU have problems with your telephone company?
Gary Chapman
David G. Novick
Laura Halliday
Al Stangenberger
Pete McVay
John Higdon
o Info on RISKS (comp.risks)

Re: You think YOU have problems with your telephone company?

Gary Chapman <chapman@csli.Stanford.EDU>
Wed, 25 Apr 90 11:37:36 PDT
The telephone system in Kissimmee sounds like the one in Moscow (the one in the
Soviet Union, not in Idaho).  Callers in Moscow are constantly getting wrong
numbers, and those who have telephones are constantly interrupted by the
telephone ringing, usually with someone who has reached the wrong number.  I
have heard people in Moscow say that the chance of getting the number that you
dialed is 50-50, and this is something that everyone has learned to live with.

As I discovered in my hotel in Moscow, the people who do ring through to your
telephone unintentionally are rarely surprised and never apologetic--in fact,
they are frequently quite chatty.  A strange form of social communication
between strangers.

Here's a story from Moscow, which is apparently fairly representative:

A man lives in an apartment building with only one telephone serving about a
hundred residents.  One day there is a fire in the building.  The man rushes to
the telephone to call the fire department.  He picks up the telephone and is
inexplicably connected to his workplace, and his boss is on the line.  The man
is momentarily flustered, the boss says, "How nice to hear from you."  The man
is a little stressed, trying to figure out how to get through to the fire
department before the fire gets out of control.

        Man:  "I'm sorry. . . "
        Boss:  "You sound upset.  What's wrong?"
        Man:  "We have a situation here."
        Boss:  "What do you want me to do?"
        Man:  "Nothing."
        Boss:  "Then why did you call me?"

I'm sure there are many more amusing (and not so amusing) effects of having a
telephone system that is so unpredictable.  The Soviet telephone system is
non-digital, of course, and still uses old cross-bar switching.  This is
unlikely to be the problem in Kissimmee, but the problems sound similar.

Gary Chapman, Executive Director, CPSR

Re: You think YOU have problems with your telephone company?

"David G. Novick" <>
Wed, 25 Apr 90 15:42:33 -0700
I had first-hand experience with a single instance of a very similar problem.
This occurred in the U S WEST Communications phone system for Eugene, Oregon,
around 1988.

A friend of mine called me from his home.  A little later I returned the call.
Instead of any normal response, the phone system responded with the
out-of-service message: three loud tones followed by "The number you have
called has been disconnected or is out of service..."  On a couple of
subsequent tries (motivated by suspicion that I made an error, followed by
disbelief), I always got the same message.  Eventually I called an operator to

It turns out that my friend's phone had been forwarded to another number,
despite the facts that (1) the other number was not a working number and (2) my
friend did not have call forwarding.  It seems to have been an internally
generated system error.  A disturbing aspect of this is that my friend could
always call out, so that his phone seemed to be working; it's just that no-one
ever seemed to call them.  It is unknown how long this state had existed.
Indeed, if the number to which the calls were being forwarded was a working
number that turned out to be either always busy or not answered, this situation
might have continued indefinitely.

David Novick

Department of Computer Science and Engineering, Oregon Graduate Institute of
Science and Technology, 19600 N.W. Von Neumann Drive, Beaverton, OR 97006-1999
   (503) 690-1156

Re: You think YOU have problems with your telephone company?

Wed, 25 Apr 1990 18:23:52 -0400
Several years ago (1984) I worked as a summer student in Bell Northern Research
(which is the research arm of Northern Telecom and has nothing to do with Bell
in the states). At the time they decided to field test one of their new SL100
switches (hope I have the right number) by making the people who made it live
with it.

Anyway, for the first month or so after the introduction of the system we
experienced problems very similar to the ones mentioned. I personally
experienced the "match-making" phenomena of having the phone ring, hearing it
ring on the other end and then having someone else answer. Very weird.

Phone calls would not only fail, but were misdirected and at times switched.
Most of these glitches ended quite quickly but it took a month or two for
everything to settle down. This was the first phone system that I had dealt
with that had all those nice features which phone companies are starting to
offer: call forwarding, call park, speed dial directories stored off the
handset etc. I'm sure that interactions between these features contributed to
the problems.  Perhaps someone at BNR remembers this episode and actually knows
something about why it happened.  It may be worth trying to contact them,
especially if it is one of their switches.


P.S. This occurred in the first few months of 1984 and it did send a good
Orwellian shiver up my spine.

Re: You think YOU have problems with your telephone company?

Amos Shapir <amos@nsc.UUCP>
Wed, 25 Apr 90 14:29:28 -0700
In Israel the (government owned) company is notorious for such incidents.
Where I live, connections to numbers in Tel Aviv starting with 4, especially 41
and 42, are sometimes close to impossible, with all the phenomena you
mentioned, especially cross-talk between lines.  The common explanation is that
this is an old exchange which is overloaded.  In any case, all this is caused
by bad hardware, mainly due to rain damage (when it rains, they have to wait
until the lines are dry before fixing anything; but then they don't know where
the cracks are!).

There are new and computerized exchanges too, but the only difference seems to
be that there such malfunctions are echoed into billing too, and of course,
they blame the computer for *everything*.
                                            Amos Shapir

National Semiconductor, 2900 semiconductor Dr., Santa Clara, CA 95052-8090
Mailstop E-280 until May 1, then back to

re: You think YOU have problems with your telephone company?

laura halliday <>
Wed, 25 Apr 90 20:10:45 PDT
The note in Risks 9.83 about the Florida woman and her telephone `service'
sounded, remarkably like a failure I saw in a C-1 electronic exchange some
years ago.

Background: the C-1 was a very early electronic exchange. It was a hybrid, with
electromechanical line equipment and a digital computer for brains. The line
equipment came in large cabinets, with cables to route calls from one cabinet
to another and more cables for status information back to the processor.

The system went crazy one afternoon. You could pick up the phone and you would
get dial tone perhaps 10% of the time. The rest of the time you'd get a mixture
of other peoples' conversations, and busy and reorder signals. The phone would
ring randomly, and you would get the same mixture of garbage if you answered

The problem turned out to be hardware. *One* wire had broken - one of those
signal wires, and, since the line equipment cabinets were daisy-chained, and
the broken wire was close to the processor, the whole thing went down. It was
buried deep inside a cable run, and took a couple of days to find.

...laura halliday, DEC Canada,

Opinions: MINE! Nothing to do with DEC Canada.

re: You think YOU have problems with your telephone company?

Wed, 25 Apr 90 18:27:26 PDT
Often when telephone installations are changed, not all wires which were
connected to the original installation are disconnected.  These residual
connections can be in a central office, on a pole, or in a building.  When a
new phone installation re-uses these apparently "dead" wires, trouble can

1.  A friend found a modular telephone jack in the basement of a house which he
just bought.  The jack had dial tone, so he used it as an extension phone.  A
couple of months later, his neighbor remarked that he had been getting billed
for long-distance calls which he had never made.  My friend recognized the
areas called as calls which he had made.  Explanation: the former occupant of
my friend's house had had two telephone numbers; the wire feeding the jack in
the basement was connected outside on the telephone pole to the same pair as
the neighbor's telephone.

2.  My parents had their telephone number changed.  They still got calls from
people dialing their old number.  The service rep at the phone company said
that was impossible -- the next call my parents got was from the service rep
dialing their old number (she was very embarassed, naturally).  Apparently a
jumper in the central office had not been disconnected so their phone rang
through two separate numbers.

3.  Many phones in my building at U.C. used to use 4-wire circuits.  When we
upgraded to 2-wire circuits (with the central office switch replacing a rack of
relays in our basement), many of the extra wires were not disconnected from the
telephones.  I've traced three problems with new phone and data line
installations to using pairs which were also connected somewhere else to a
telephone although the wires were not used for dial tone.

Al Stangenberger, Dept. of Forestry & Resource Mgt., 145 Mulford Hall - Univ.
of Calif., Berkeley, CA 94720          BITNET: FORAGS AT UCBVIOLE (415) 642-4424

re: You think YOU have problems with your telephone company?

Pete McVay, TAY2-2/F14, 227-3598 <>
26 Apr 90 10:24
 I worked with a network security organization a few years ago.  While my job
did not directly involve phone phreak investigations (those individuals who
attempt to hack "telecommunications" rather than "computers"), I did overhear
some information that seems to fit in with the Kissimmee woman's phone
problems--that is:

    o some hackers were known to have infiltrated major telephone networks
          and set up their own trapdoors and Trojan Horses in the switching
          software.  The statement was made that "many telecommunications
          vendors are not in control of their own systems".

    o there was evidence that at least one phone phreak could do anything
          in a major phone system that the owners could--that is, grant
          services (call forwarding, etc.), disconnect or enable phone
          service, and change billing.  This included the ability to make
          "invisible" (non-charged and unrecorded) long-distance phone calls.

    o some of this ability was used for harassment: law-enforcement
      officials and/or people the phone phreak personnally did not like
      receive huge phone bills.  Friends of phone phreaks found their
      bills greatly reduced.

 The one item that does not fit, however, is the visibility of this woman's
problems.  Typically the phone phreaks kept their activities quiet: advertising
them would spark an investigation and possible breakup of their access.  Such
harassment that did go on was minor and was not on a continuing scale such as
this woman described.  But maybe she antagonized a phone phreak in a major way:
could she be a prominent community activist on social or environment issues,
for example?

re: You think YOU have problems with your telephone company?

John Higdon <>
26 Apr 90 00:06:41 PDT (Thu)
Missing details in the mysterious case of the Florida woman experiencing much
trouble with her telephone service make intelligent comment impossible.
Probably most the most important consideration would be the type of central
office switch involved. Since we are not dealing with an RBOC, it could be
anything; some of those off-the-wall switches are capable of some rather
bizzare behavior. Also, it is significant if this is rural service.

The "crossed line" problems sound like difficulties associated with "pair gain"
equipment. To make an outdated, undersized outside plant serviceable, telcos
sometimes resort to concentrators. These are devices that allow many
subscribers to have what appear to be private lines over a somewhat smaller
number of actual circuits. This is not to be confused with digital "remote"
offices, which actually provide the functional equivalent of private lines
(within their blocking factor limitations) over digital carrier back to the
host central office.  Concentrators are fraught with difficulty, most of it
similar to the "crossed wire" effect observed by our subject.

All in all, it sounds as if our hapless woman is plagued with problems
resulting from multiple causes: difficulty with the 800 carrier, possible CO
trouble, possible outside plant trouble, etc. In my library of telephone
experience, I have never had anything to compare with our Florida victim, but
my universal solution might be something to consider.

On several occasions, I have had difficulty of one sort or another that the
telco simply has not been able to correct. Either it has been of an
intermittant nature and not detectable by test personel or the solution has
just simply eluded the maintenance staff. When it appears that the difficulty
cannot be corrected in a timely manner, I order a new service. After the new
service is completely installed, the old (and troublesome) service is
disconnected. This ensures that no part of the old service remains; not the
cable pair, CO line equipment, nor any line conditioners or loop extenders.
This tactic has not failed to correct seemingly "insoluble" problems.

Another consideration: if this woman is the victim of someone's maliciousness
(a real possiblity) then the solution might be elusive.  This "someone"
obviously has software (and most likely hardware) access to the telco and could
be very hard to track down. A second, more likely but almost as difficult to
deal with, possiblity is that the telco is just plain messed up. In that case
my "universal solution" might correct her current problems and bring on others.

In any event, I would be very interested in getting further details. If her
area code/prefix could be revealed, I can determine what type of CO switch is
involved. Also, I can probably research what type of outside plant we are
dealing with. Solutions are not guaranteed, but the finger pointing might
become a little more educated.

John Higdon, P. O. Box 7648, San Jose, CA 95150           +1 408 723 1395

re: You think YOU have problems with your telephone company?

Thu, 26 Apr 90 02:31 CST
Well, this may not be related to a phone company problem, but when I was an
undergrad, the university decided to go from party line rotary phones, to a
brand-spanking-new digital switch and give everyone their own private line.

No problem right? Well you know the answer to this one.  Not only did we get
our own phone lines, but all the neato features that come with a digital
switch such as call forwarding, speed dial, three way call, call waiting,
etc...And the ability to have a "secret" 5 digit code to bill your calls to.

Due to a "programming error" it was quickly discovered that you could use your
"secret" code from any telephone on campus.  And of course if you happened to
incorrectly enter your "secret" code at another phone, chances were that it was
someone elses "secret" code that you entered, and the call would go through!
Of course when that person's bill came, it showed up as a call from a phone
they werent at for a number they didnt call.  So of course the local telephone
people on campus got this bug fixed -- after about a month and an unknown # of
"misentered" secret codes...

After this fix, another neat thing would show up.  During the late hours of the
night (when all the CS hackers do their things and make avid use of all the
modem lines on campus), the digital switch would tend to "hang", and would not
produce a dial tone.  Sometimes it would actually connect you as an additional
party to a conversation in progress and although you could hear both sides of
the conversation -- they couldnt hear you no matter what tone you sent or how
loud you screamed.  After the two parties hung up, if you stayed on the line,
you would be connected to the next phone call which either of those two parties
made -- although they could hear you this time.  However they could not dial,
and until you hung up they couldnt dial.  Through some trial and error, a
friend of mine and I discovered that by hitting *99 (which would kill all of
your personal speed dial #'s), that the entire switch would reset -- loosing
all the speed dial #'s, and other pre-programmed goodies...

Needless to say, after reporting this occurance the university did nothing, so
we talked to the makers of the switch -- GTE, and they came out and fixed
it...  No problems since then.

Moral of the story: Software controls our lives, and is written by people who
are subject to sleeplessness, caffeine (or other drug addictions), or just
plain forgetfullness (how many times have you left out a { in some C code?).
We had all better be aware of the risks, and do the best we can...

Greeny          BITNET: MISS026@ECNCDC

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