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Tolmes News Service 12
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# > Written by Dr. Hugo P. Tolmes < #
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Issue Number: 12
Release Date: November 19, 1987
This entire issue is an article about blue boxing.
Notice: This article is full of errors that most phreaks will catch.
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
TITLE: The Blue Box an Ma Bell
FROM: Radio Electronics
DATE: November 1987
-WHEN BLUE AND READ MEANT THE TRASHING OF MA BELL............
Before the Breakup of AT&T, Ma Bell was everyone's favorite enemy. So
it was not suprising that so many people worked so hard and so
successfully at perfecting various means of making free and untraceable
telephone calls. Whether it ws a Red box used by Joe and Jane College to
call home, or a blue box used by organized crime to lay off untraceable
bets, the technology that provided the finest telephone system in the world
contained the seeds of its own destruction. The fact of the matter is that the
blue box was so effective at making untraceable calls that there is no
estimate how many calls were made or who made them. No one knows for certain
whether Ma Bell los revenues of $100,$100-million, or $1 billion on the
Blue Box.
Blue Boxes were so effective at making free, untraceable calls that Ma
Bell didn't want anyone to know about them, and for many years denied their
existence. They even went as far as strong-arming a major consumer-science
magazine into killing an article that had been prepared on the Blue and Red
boxes. Further, the police records of a major city contain a report concerning
a break-in at the residence of the author of the article. The only item
missing following the break-in was the folder containing copies of one of the
earliest Blue-Box designs and a Bell-system booklet that described how
subscriber billing was done by the AMA machine-a boklet that Ma Bell denied
ever existed; Fig. 1 proves otherwise.
Since the AMA (Automatic Message Accounting) machine was th means whereby
Ma Bell eventually tracked down both the Blue and Red boxes, we'll take time
out to explain it. Besides, knowing how the AMA machine works will help you to
better understand Blue and Red Box "phone phreaking."
WHO MADE THE CALL?
Back in the early days of the telephone, a customer's billing
originated in a mechanical counting device, which was usually called a
"register" or a "meter." Each subscriber's line was connected to a
meter that was part of a wall of meters. the meter clicked off the message
units, and once a month someone simply wrote down the meter's reading, which
was later interpolated into message-unit billing for the subscriber's who
wunit. (Flat-rate subscriber's could make
unlimited calls only within a designated geographic area. The meter clicked
off message units for the calls outside the area.) Because eventually there
were too many meters to read individually, and because more subscribers
started questioning their monthly bills, the local telephone companies
turned to photography.
A photograph of a large number of meters served as an inconstestable
record of their reading at a given date and time, and was much easier to
convert to customer billing by the accounting department. As you might
imagine, even with photographs billing was cumbersome and did not reflect the
latest technical developments. a meter didn't provide any indication of what
the subscriber was doing with the telephone, nor did it indicate how the
average subscriber made calls or efficiency of the information service (how
fast the operators could handle requests). So meters were replaced by
the AMA machine. One machine handled up to 20,000 subscribers. It produced a
punched tape for a 24-hour period that showed, among other things, the time
the phone was picked up for (went off-hook).
One other point, which will answer some questions that you're certain to
think of as we discuss the Red and Blue boxes: Ma Bell did not want person
outside their system to know about the AMA machine. The reason? Almost
everyone had complaints-usually unjustified-about their billing. Had
the public been aware of the AMA machine they would have asked for a
monthly list of their telephone calls. It wasn@t that Ma Bell feared errors in
billing; rather, they were fearful of being buried under an avalanche of
paperwork and customer complaints. also, the public believed their
telephone calls were personal and untraceable, and Ma Bell didn't want to
admit that they knew about the who,
what, and where of every call. and so Ma Bell always insisted that billing
was based on a meter that simply "clicked" for each message unit; that
thee was no record, other than for the long-distance calls, as to who called
whom.
Long distance was handled by, and the billing information ws done by and
operator, so ther was a written record Ma Bell could not deny. The secrecy
surrounding the AMA machine was so pervasive that local, state, and even
federal police were told that local calls made by criminals were
untraceable, and that people who made obscene telephone calls could not be
tracked down unless the person receiving the call could keep the caller
on the line for some 30 to 50 minutes so the connections could be physically
traced by technicians. Imagine asking woman or child to put up with almost an
hour's worth of the most horrendous obscentities in the hope someone could
trace the line.
Yet in areas where the AMA machine had replaced the meters, it would have
been a simple, though perhaps time-consuming task, to track down the numbers
called by any telephone during a 24-hour period. but MaBell wanted the AMA
machine kept as secret as possible, and so many a criminal was not caught, and
many a w by obscene calls of a potential rapist, because
existance of the AMA machine was denied. As a sidelight as to the
secrecy surrounding the AMA machine, someone at Ma Bell or the local
operating company decided to put the squeeze on the author of the article on
Blue Boxes, and reported to the Treasury Department that he was, in
fact, manufacturing them for organized crime- the going rate in the mid 1960's
was supposedly $20,000 a box. (Perhaps Ma Bell figured the author would get
the obvious message: Forget about the Blue Box and the AMA machine or you'll
spend lots of time, and much money on lawyer's fees to get out of the hassles
it will cause.)
The author was suddenly visited at his place of employment by a Treasury
agent. Fortunately, it took just a few minutes to convince the agent that the
author was really just that, and not a technical wizard working for the mob.
but one conversation led to another, and the Treasury agent was astounded to
learned about the AMA machine. (Wow! Can and author whose story is squelched
spill his guts.) According to the Treasury agent, his department had been told
that it was impossible to get a record of local calls made by gangsters; the
Treasury department had never been informed of the existance of automatic
message accounting. Needless to say,
the agent left with his own copy of the Bell System publication about the AMA
machine, and the author had an appointment with the local Treasury-Bureau
director to fill him in on the AMA machine.
That information eventually ended up with Senator Dodd, who was conducting
a congressional investigation into, among other things, telephone company
surveillance of subscriber lines- which was a common practice for which there
was detailed instructions, Ma Bell's own switching equipment ("crossbar")
manual.
THE BLUE BOX
The Blue Box permitted free telephone calls because it used Ma Bell's
own internal frequency-sensitive circuits. When direct long-distance
dialing ws intorduced, the crossbar equipment knew a long-distance call was
being dialed by the three-digit area code. The crossbar then converted the
dial pulses to the CCITT tone groups, shown in Taple 1, that are used for
international and trunkline signaling. (Note that those do not correspond to
Touch-Tone frequencies.) As you can see in that table, the tone groups
represent more than just numbers; among other things there are tone groups
identified as KP (prime) and ST (start)- keep them in mind.
When a subscriber dialed an area code and a telephone number on a
rotary-dial telephone, the crossbar automatically connected the subscriber's
line to a long-distance trunk, converted the dial pulses to CCITT tones,
set up electronic cross-country signaling equipment, and recorded the
originating number and the called number on the AMA machine. the CCITT
tones sent out on the long-distance trunk lines activated special equipment
that set up or selected the routing, and caused electro-mechanical equipment
in the target city to dial the called telephone. Operator-assisted
lls worked the same way. The operator simply logged into a
long-distance trunk and pushed the appropriate buttons, which generated
the same tones as direct-dial equipment.
The button sequence was KP (which activated the long-distance equipment),
then the complete area code and telephone number. At the target city,
the connection was made to the called number but ringing did not occur until
the operator there pressed the ST button. The sequence of events of
early blue Boxes went like this; The caller dialed information in a distant
city, which caused his AMA machine to record a free call to information. When
the information operator answered, he pressed the KP key on the Blue Box,
which disconnected the operator and gave him access to a long-distance
trunk. He then dialed the desired number and ended with an ST, which
cuased the target phone to ring. For as long as the conversation took place,
the AMA machine indicated a free call to an information operator.
The technique required a long-distance information operator because
the local operator, not being on a long distance trunk, was accessed through
local wire switching, not the CCITT tones.
CALL ANYWHERE
Now imagine the possibilities. Assume the Blue Box user was in
Philadelphia. He would call Chicago information, disconnect from the
operator with a KP tone, and then dial anywhere that was on direct-dial
service: Los Angeles, Dallas, or anywhere in the world if the Blue Box
could get the international codes. The legend is often told of one blue Boxer
who, in the 1960's, lived in New York and ahd a girl friend at college near
Boston. Now back in the 1960's, making a telephone call to a college town on
the weekend was even more difficult that it is today to make a call from
New York to Florida on a reduced-rate holiday using one of the cut-rate
long-distance carriers. So our Blue Boxer got on an international
operator's circuit to Rome, Blue Boxed through to a Hamburg operator, and
asked Hamburg to patch through to Boston. The Hamburg operator thought
the call originated in Rome and inquired as to the "operator's" good
english, to which the Blue boxer replied that he was an expatriate hired
to handle calls by American routists back to their homeland. Every weekend,
while the Northeast was stranged by reduced-rate long-distance calls, our
Blue Boxer had no trouble sending his voice almost 7,000 miles for free.
VACUUM TUBES
Assembly plans for blue boxers were sold through calssified
advertisements in the electronic-hobbyist magazines. One of
the earliest designs was a two-tube portable model that used a 1.5 volt "A"
battery for the filaments and a 125-volt "B" battery for the high
voltage (B+) power supply. The portable blue box's functional circuit is shown
in Fig. 2. It consisted of two pase-shift oscillators sharing a common speaker
that mixed the tones from both oscillators. Switches s1 and s2 each
represent 12 switching circuits used to generate the tones. (No, we will not
supply a working circuit, so please don't write in and ask- e user placed
the speaker over the telephone handset's transmitter and
simply pressed the buttons that corresponed to the desired CCITT tones. It was
just that simple. Actually, it was even easier than it reads because Blue
Boxers discovered they did not need the operator. If they dialed an active
telephone located in certain nearby, but different, area codes, they could
Blue Box just as if they had Blue Boxed trhough an information operator's
circuit. The subscriber whose line was Blue Boxed simply found his phone was
dead when it was picked up. But if the Blue box conversation ws short, the
"dead" phone suddenly came to life the next time it ws picked up.
Using a list of "distant" numbers, a Blue Boxer would never hassle anyone
enough time to make them complain to the telephone company. The difference
between Blue Boxing off of a subscriber rather than an information operator was
the the Blue Boxer's AMA tape indicated a real long-distance telephone call-
perhaps costing 15 or 25 cents- insted of a freebie. Of course, that is the
reason why when Ma Bell finally decided to go public with the "assisted"
newspaper articles about the Blue Box usuers they had apprehened, it was
usually some college kid or "phone phreak". One never read of a mobster
being caught. Greed and stupidity were the reasons why the kids were caught.
It was the transistor that led Ma Bell going public with the Blue Box. By
using transistors with RC phase-shift networks for the oscillators, a portable
blue Box could be made inexpensively, and small enough to be used
unobtrusively from a public telephone. The college crowd in many technical
schools went crazy with the portable Blue Box; they could call the folks
back home, their friends, or get a free network (the Alberta and Carolina
connections- which could be a topic for a whole separate article) and never pay
a dime to Ma Bell. Unlike the mobsters who were willing to pay a small
long-distance charge when Blue Boxing, the kids wanted it, wanted ti all free,
and as they used the information operator routing, and would often talk
"free-of-charge" for hours on end.
Ma Bell finally realized that Blue Boxing was costing them Big Bucks, and
decided a few articles on the criminal penalties might scare the Blue Boxers
enough to cease and desist. But who did Ma Bell catch? The college kids and the
greedies. When Ma Bell decided to catch Blue Boxers she simply examined the AMA
tapes for calls to an information operator that were excessively long. No one
talked to an operator for 5, 10, 30 minutes, or several hours. Once a long
call to an operator appeared several times on an AMA tape, Ma Bell simply
monitored the line and the Blue Boxer was caught. (Now do you understand why
we opened with the explanation of the AMA machine?)
If the Blue Boxer worked from a telephone booth, Ma Bell simply
monitored the booth. Ma Bell might not have known who originated the call, but
she did know who got the call, and getting that party to spill their guts
was not problem. The mob and a few Blue Box h even
thousands) knew of the AMA machine, and so they used a real telephone number
for the KP skip. Their AMA tapes looked perfectly legitimate. Even if Ma Bell
had told the authorities they could provide a list of direct-dialed calls
made by local mobsters, the AMA tapes would never show who was called through
a Blue Box. For example, if a bookmaker in New York wanted to lay off some
action in Chicago, he would make a legitimate call to New Jersey. Nowhere
would there be a record of the call to Chicago. Of course, automatic tone
monitoring, computerized billing, and ESS (Electronic Switching Systems) now
makes that all vitually impossible, but that7s the way it was. You might wonder
how Ma Bell discovered the tricks of the Blue Boxers. Simple, they hired the
perpetrators as consultants.
While the initial newspaper articles detailed the potential jail
penalties for apprehended Blue Boxers, except for Ma Bell employees who
assisted a Blue Boxer, it is almost impossible to find an article on the
resolution of the cases because most hobbyist Blue boxers got suspened
sentences and/or probation if they assisted Ma Bell in developing
anit-Blue Box techniques. It is asserted, although it can't be easily
proven, that cooperating ex-Blue Boxers were paid as consultants. (If you can't
beat them, hire them to work for you.) Should you get any ideas about Blue
Boxing, keep in mind that modern switching equipment has the capacity to
recognize unauthorized tones. It's the reason why a local office can leave
their subscriber Touch-Tone circuits active, almost inviting you to use the
Touch-Tone service. A few days after you use an unauthorized Touch-Tone
service, the business office will call and inquire whether you'd like to pay
for the service or have it disconnected. The very same central-office
equipment that knows you're using Touch-Tone frequencies knows if you
line is originating CCITT signals.
THE RED BOX
The Red Box was primarily used by the college crowd to avoid charges when
many calls were made between two particular locations, say the college
and a student's home. Unlike the somewhat complex cicuitry of a Blue Box,
a Red Box was nothing more than a modified telephone; in some cases nothing
more than a capacitator,a momentary switch, and a battery.
As you recall from our discussion of the Blue Box, a telephone circuit is
really established before the target phone ever rings, and the circuit is
capable of carrying an AC signal in either direction. When the caller hears
the ringing in his or her handset, nothing is happening at the receiving
end because the ringing signal he hears is really a tone generator at his local
telephone office. The targe (called) telephone actually gets 20
pulses-per-second ringing voltage when the person who dials hears nothing- in
the "dead" spaces between hearing nothing and the ringing tone. When the
called phone is answered and taken off the hook, the telephone compleats a
local-office DC loop that is the signal to stop the ringing voltage. About
three seconds later the Din a signal being sent all the way back
to the caller's AMA machine that the called the telephone was answered. Keep
that the three-second AMA delay in mind. (By now you should have a pretty
good idea of what's coming!) Figure 3 shows the simplified functonal
schematic of the telephone. Switch S1 is the hook switch. When S1 is open
(on-hook) only the ringer circuit consisting of C1 and BELLI is connected
across the line. Capacitator C1 really has no purpose in the ringing ciruit;
it only serves to keep the DC from flowing through BELLI. When the local
telephone office feeds a 20-pps ringing signal into the line it flows though c1
and a ringer coil in BELLI. A vibrating device attached to BELLI strikes a
small ball- the ringing device. When the phone is answered by lifting the
handset across from its cradle, switch s1 closes (goes off-hook) and connects
the handset across the telephone line. since the handset's receiver and
transmitter (microphone) are connected in series, a DC path is established fro
one side of the line to the other- what is called completing a DC loop with the
central office.
The DC current flowing in the loop causes the central office to instantly
stop the ringin signal. When the handset is replaced in its cradle, s1 is
opened, the DC loop is broken, the circuit is clear, and a signal is sent
to the originating telephon's AMA machine that the called party has
disconnected. Now as we said earlier, the ciruit can actually carry AC before
the DC loop is closed. The Red Box is simply a device that provides a
telephone with a local battery so that the phone can generat and AC signal
without having a DC connection to the phone line. The earliest of the Red
Boxes was the surplus military field telephone, of which there were
thousands upon thousands in the marketplace during the 1950's and
1960's. The field telephone was a portable telephone unit having a manual
ringer worked by crank- just like the telephone Grandpa used on the farm -and
two D-cells. A selector switch set up the unit so that it functioned as a
standard telephone that could be connected to a combat switchboard, with
the DC power supplied by the switchboard. but if a combat unit wasn't
connected to a switchboard, and the Lieutenant yelled "Take a wire," the
signalman threw a switch on his field telephone that switched in the local
battaries.
To prevent the possibility of having both ends of the circuit feeding
battery current into the line in opposit polarity- therby resulting in
silence -the output from the field telephone was running from its internal
batters ws only the AC representing voice input, not modulated DC. Figure 4
is the functional simplified schematic for a field telephone (do not attempt
fo build that ciruit). Momentary switch s4 is not part of the field
telephone, it is added when the phone is converted to a Red Box; so for now,
consider that S4 does not exist. Once again, S1 is the hook switch. When S2
is set to N (NORMAL) and S1 is closed, DC flows from line A through T1's
secondary (S), through S2-a to S2-b,rimary (P), through the
handset, through S2-c, to line B.
There is a complete DC path across the line, and if the unit is connected
across a conventional subscriber telephone line it will close the Dc loop
from the local office. to use the field telephone as a Red Box, switch S2 is
set to L (LOCAL). Switches S2-b and S2-c connect batteries B1 and B2 in
series with the handset and the transformer's primary, which constitute
an active, working telephone ciruit.
Switch S2-a connects T2's secondary to one side of the telephone line through
a non-polarized capacitator (C1), so that when hook-switch S1 is closed,
T1's secondary cannot close the Dc loop.
PRESS ONCE TO TALK
The Red Box was used at the receiving end; let's assume it's the
oldhomestead. The call was originated by Junior (or Sis) at their college
1000 miles from home. Joe gave the family one ring and hung up, which told
them that he's calling. Pop set up the Red Box by setting S2 to LOCAL. Then
Junior redialed the old homestead. Pop lifted the handset when the phone rang,
which closed S1. Then Pop closed momentary-switch S4 for about a
half-second, which caused the local telephone office to silence the ringing
signal. When Pop release S4, the folks can talk to Junior without Junior
getting charged because his AMA tape did not show his call was answered- the
DC loop must be closed for at least three-seconds for the AMA tap to show
Junior's call was answered.
All the AMA tape showed is that Junior let phone at the old homstead
ring for almost 30 minutes; a length of time that no Bell Operating Company is
likely to believe twice! A modern Red Box is simply a conventional telephone
that's been modified to emulate the vintage 1940 military field telephone.
Aside from the fact that the operating companies can now nail every Red Box
user because all modern billing equipment shows the AMA information
concerning the length of time a caller let the target phon ring, it's use has
often put severe psychological strain on the users.
Does getting electronics mixed up with psychology sound strange? Well it
isn't because it's what helped Ma Bel put an end to indiscriminate use of the
Red Box. The heyday of the Red Box was the 1950's and 1960's. Mom and Pop were
lucky to have finished high school, and almost without exception, both
elementry and high schools taught honesty and ethics. Mom and Pop didn't have
the chance to take college courses like Stealing 101 that masqueraded under
quaint names such as Business Management, Marketing, o Arbitrage.
When Junior tried to get the old folkes to use his "free telephone" they
just wouldn't go along. So Junior installed the Red Box on his end. He gave
one ring to notify the family to call him back. When Pop called Junior, it
was Junior who was using the Red Box. Problem was, Junior didn't know that
the AMA tapes for Mom and Pop's phone showed a 20- or 30-minute ringing. When
Ma Bell's investigators showed up it was only then that the folks discovered
their pride and joy had been taught to steal. There are nncering how many Red
Boxes were in use, or how much money Ma Bell lost, but one thing is known:
she had little difficulty in closing down Red Boxes in virtually all instances
where the old folks were involved because Mom and Pop usually would not
tolerate what to them was stealing. If you as a reader have any ideas about
using a Red Box, bear in mind that the AMA (or its equivalent) will get you
every time, even if you use a phone booth, because the record will show the
number being called, and as with the Blue Box, the people will spill their
guts to the cops.
