With thanks to Peter McIvers for the list of frequencies mentioned later in
this phile.
NOTE: the British Post Office, is the U.S. equivelent of Ma Bell.
In Britain, phreaking goes back to the early fifties, when the technique of
'Toll A drop back' was discovered. Toll A was an exchange near St. Pauls which
routed calls between London and nearby non-London exchanges. The trick was to
dial an unallocated number, and then depress the reciever-rest for 1/2 second.
This flashing initiated the 'clear forward' signal, leaving the caller with an
open line into the Toll A exchange. He could thjen dial 018, which forwarded
him to the trunk exchange- at that time, the first long distance exchange in
Britain- and foll ow it with the code for the distant exchange to which he
would be connect ed at no extra charge.
The signals needed to control the UK network today were published in the
"Institution of Post Office Engineers Journal" and reprinted in the Sunday
Times (15 Oct. 1972).
The signalling system they use: signalling system No. 3 uses pairs of
frequencies selected from 6 tones separated by 120Hz. With that info, the
phreaks made "Bleepers" or as they are called here in the U.S. "Blue Box", but
they do utilize different MF tones then the U.S., thus, your U.S. blue box that
you smuggled into the UK will not work, unless you change the frequencies.
In the early seventies, a simpler system based on different numbers of
pulses with the same frequency (2280Hz) was used. For more info on that, try to
get ahold of: Atkinson's "Telephony and Systems Technology".
The following are timing and the frequencies for boxing in the UK and other
foreign countries. Special thanks to Peter McIvers for the phollowing inpho:
British "bleeper" boxes have the vaery same layout as U.S. blue boxes. The
frequencies are different, though. They use two sets of frequencies, forward
and backward. Forward signals are sent out by the bleeper box; the backward
signals may be ignored (it's sort of like using full duplex). The frequencies
are as follows:
U.S.:
US: 700 900 1100 1300 1500 1700
Forward: 1380 1500 1620 1740 1860 1980 Hz
Backward: 1140 1020 900 780 660 540 Hz
for example, change the 900 Hz potentiometers in your box to 1500 Hz. All
numbers 1-0 (10) are in the same order as in an American box. The ones after
this are thier codes for operator 11, operator 12, spare 13, spare 14, and 15.
One of these is KP, one (probably 15) is Star; it won't be too hard to figure
out. The signals should carry -11.5dBm +/- 1dB onto the line; the frequencies
should be within +/- 4Hz (as is the British equipment). Also, the 1VF system is
still in operation in parts of the U.K. This would encode all signals 1 to 16 as binary numbers; for instance, a five is 0101. There are six intervals per
digit, each 50ms long r a total of 300ms. First is a start pulse of 2280 for
50ms. Then, using the example of five (0101), there is a 50ms pause, a 50ms
pulse of 2280, a 50ms pause, and a 50ms pulse of 2280. Finally, there is a
50ms pause that signals the end of the digit. The frequency tolerance on the
2280 Hz is +/- 0.3%; it is sent at -6 +/- 1dBm. An idle line is signaled by
the presence of a 3825Hz tone for more than 650ms. This must be within 4Hz.
France uses the same box codes as the US, with an additional 1900Hz
acknowledgement signal, at -8.7 +/- 1dBm per frequency.
Spain uses a 2 out of 5 mf code (same frequencies as US), with a 1700 Hz
acknowledge signal.
Other places using the 1VF system are:
Australia, 2280Hz +/-6Hz, 35ms/digit at -6dB.
Germany, France: same as Australia; also, some 1VF systems in the UK.
Switzerland: same as Australia, only it uses 3000Hz, not 2280.
Sweeden: same as above, but at 2400Hz.
Spain: some parts use 1VF with 2500Hz.
There is one other major system: the 2VF system. In this system, each digit is
35ms long. The number is encoded in binary as with the 1VF system. Using the
example of five (0101), here's how the American 2VF system was sent:
(about twice a second), at -28.5 to -22.5 dBm/tone.
Ring: 440+480 Hz at -23.5 to -20.5 dBm/tone.
A ring is modulated at 20 +/- 3Hz, 2sec on, 4sec off.
Call waiting: 440Hz, on 1 second.
Recorder Connection: 1400Hz, beeps every 15minutes.
Multiparty line ring: sam% frequency and modulation as ring, but 1sec on, 2sec
off (twice as fast).
Now, back to British Phreaking:In the early days of British phreaking, the
Cambridge University Titan Computer was used to record and circulate numbers
found by the exhaustive dialing of local networks. These number s were used to
create a chain of links from local exchange to local exchange across the
country, bypassing the trunk circuits. Because the internal routing codes in
the UK network are not the same as those dialed by the caller, the phreaks had
to discover them by 'probe and listen' techniques or more commonly known in the
U.S.--SCANNING. What they did was put in likely signals and listened to find
out if they succeeded. The results of scanning were circulated to other
phreaks. Discovering each other took time at first, but evenutally the phreaks
became organized. The "TAP" of Britain was called "Undercurrents" which enabled
British phreaks to share the info on new numbers, equipment etc.
To understand what the British british phreaks did, think of the phone
netowrk in three layers of lines: Local, trunk, and international. In the UK,
Subcriber Trunk Dialing (STD), is the mechanism which takes a call from the
local lines and (legitimately) elevates it to a trunk or international
level. The UK phreaks figured that a call at trunk level can be routed through
any number of exchanges, provided that the right routing codes were found and
used correctly. They also had to discover how to get from local to trunk level
either without being charged (which they did with a bleeper box) or without
using (STD). Chaining has already been mentioned but it requires long strings
of digits and speech gets more and more faint as the chain grows, just like
it does when you stack trunks back and forth accross the U.S. The way the
security reps snagged the phreaks was to put a simple 'printermeter' or as we
call it: a pen register on the suspects line, which shows every digit dialed
from the subscribers line.
The British prefer to get onto the trunks rather than chaining. One way was
to discover where local calls use the trunks between neighboring exchanges,
start a call and stay on the trunk instead of returning to the local level on
reaching the distant switch. This again required exhaustive dialing and made
more work for Titan; it also revealed 'fiddles', which were inserted by Post
Office Engineers. What fiddling means is that the engineers rewired the
exchanges for thier own benefit. The equipment is modified to give access to a
trunk with out being charged, an operation which is pretty easy in Step by Step
(SXS) electromechanical exchanges, which were installed in Britain even in the 1970s (NOTE: I know of a back door into the Canadian system on a 4A CO., so if
you are on SXS or a 4A, try scanning 3 digit exchanges, ie: dial 999,998,997
etc. and listen for the beep-kerchink, if there are no 3 digit codes which
allow direct access to a tandem in your local exchange and bypasses the AMA so
you won't be billed, not have to blast 2600 every time you wish to box a call.
A famous British 'fiddler' revealed in the early 1970s worked by dialing 173.
The caller then added the trunk code of 1 and the subscribers local number. At
that time, most engineering test services began with 17X, so the engineers
could hide thier fiddles in the nest of service wires. When security reps
started searching, the fiddles were concealed by tones signalling: 'number
unobtainalbe' or 'equipment engaged' which switched off after a delay. The
necessary relays are small and easily hidden.
$There was another side to phreaking In the UK in the sixties. Before STD was
widespread, many 'ordinary' people were driven to occasional phreaking from
sheer frustration at the inefficient operator controlled trunk system.
This came to a head during a strike about 1961 when operators could not be
reached. Nothing complicated was needed. Many operators had been in the habit
of repeating the codes as they dialled the requested numbers so people soon
learnt the numbers they called frequently. The only 'trick' was to know which
exchanges could be dialled through to pass on the trunk number. Callers also
needed a pretty quiet place to do it, since timing relative to clicks was important
The most famous trial of British phreaks was called the Old Baily trial. Which
started on 3 Oct. 1973. What they phreaks did was to dial a spare number at a
local call rate but involving a trunk to another exchange Then they send a
'clear forward' to thier local exchange, indicating to it that the call is
finished;but the distant exchange doesn't realize because the caller's phone is
still Off the hook. They now have an open line into the distant trunk exchange
and sends to it a 'seize' signal: '1' which puts him onto its outgoing lines.
Now, if they know the codes, the world is open to them. All other exchanges
trust his local exchange to handle the billing; they just interpret the tones
they hear. Mean while, the local exchange collects only for a local call. The
investigators discovered the phreaks holding a conference somewhere in England
surrounded by various phone equipment and bleeper boxes, also printouts listing
'secret' Post Office codes. (They probably got them from trashing?) The judge
said: "some take to heroin, some take to telephones" for them phone phreaking
was not a crime but a hobby to be shared with phellow enthusists and discussed
with the Post Office openly over dinner and by mail. Their approach and
attitude to the worlds larges computer, the global telephone system, was that
of scientist s conducting experiments or programmers and engineers testing
programs and systems. The judge apeared to agree, and even asked them for
phreaking codes to use from his local exchange!!!
$-The End-$
Look for my other phine philes: The History Of E.S.S.
Electronic Toll fraud devices (Boxes)
Bell Security Tactics
& other typed in philes on many subjects.
And coming soon to a Phreak Board near You: All you ever wanted to know about
any Central Office, from SXS, PANEL to E.S.S. #1.
Later on......$-=>Lex Luthor<=-$
Remote sysop of Plover-net 516-935-2481 and Sysop of: The Legion Of Doom!
305-COE-XXXX
If your good, you'll find out the #.
[Courtesy of Sherwood Forest ][ -- (914) 359-1517]
