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From: kf5iw!jim@central.uucp (Jim Blocker)
Newsgroups: comp.dcom.telecom
Subject: Ripping-off Ma Bell in 1975
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Date: 5 Oct 90 02:20:01 GMT
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X-Telecom-Digest: Volume 10, Issue 715, Message 1 of 8


Recent talk in the Digest regarding the "censored" _Ramparts_ article
on how to steal from Ma Bell made me remember a three-part series of
articles that appeared in _73 Magazine_ (an amateur radio magazine)
back in 1975.  These articles were probably very damaging to TPC since
explicit details were provided in one of the articles on how to bypass
coin-phone and long distance charges.

These articles were very well written and provided me with a lot of
insight as to how telephones and the network operated back then.  Even
though none of the circuits presented in the articles could today be
used to defraud TPC (except maybe the "Red Box" :)), they are still
interesting from a historical perspective.

The author of all three articles was Spenser Whipple, Jr.  Here is a
brief summary:

  April 1975: "Lifting Ma Bell's Cloak of Secrecy" described how a telephone
  set worked, various tones in the network (dial tone, busy, re-order,
  ringback), and DTMF generators.

  May 1975: "Inside Ma Bell" described how TPC detected "unauthorized"
  equipment on your line, how to defeat that detection, and "couplers" for
  attaching "foreign" equipment to your phone line.

  June 1975: "Inside Ma Bell" was the most damaging (at least to Ma Bell)
  of the three articles.  It described some more "couplers", but of greater
  interest were the details on how to build a "Black Box", "Red Box", and
  the infamous "Blue Box", all devices intended to defraud TPC.

The "Black Box" was merely a simple modification to a standard
telephone set which allowed one to receive telephone calls without
returning an "off-hook" indication to the CO.  This worked back then
because a "talk path" was established during ringing of the called
telephone.  By using a blocking capacitor and resistor, you could
establish an AC connection (talk path) and talk in between ringing.
Since no DC connection was made, the CO never detected the call being
answered and the call wasn't billed to the caller.

The "Red Box" was used to send coin tones and make free calls from pay
phones.  The June 1975 article gives two different designs -- one
using many transistors, and the other using a couple of IC's.  Even
though modern-day pay telephones contain circuitry to determine if
coins have actually been inserted or not, there may still be some pay
phones where the "Red Box" may work.

Two designs were given for the "Blue Box".  Again, one using many
transistors and the other using a couple of IC's.  This particular
color of box was the most powerful of the three in that it allowed one
to send the famous 2600 Hz tone as well as the MF tones that were used
for in-band signalling.  In the proper hands, this box could be used
to place long distance calls virtually anywhere at no charge.

Since the telephone network has changed greatly since these articles
were written, I doubt very much that any of this information could be
used to defraud any local or long distance telephone company.

Inquire at your local library to see if they have these old issues.
They make for some very interesting reading!


Jim Blocker                   jim%kf5iw@rwsys.lonestar.org
KF5IW                         ..!letni!rwsys!kf5iw!jim