There was also another technique people used in those days.  In New Orleans,
we called them spook lines which meant that if enough people called a number
while it was busy, you could talk to each other through the busy signal.  Of
course this caused problems for the owners of those numbers because they
were almost never not busy, and phone companies solved that problem by
putting more resisters on those numbers making the busy signal very much
louder.  
Harvey

-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Martin G. McCormick
Sent: Wednesday, May 6, 2015 9:29 PM
To: [log in to unmask]
Subject: Re: Before There Was Caller I D

	That sounds like it might have been a beige box. They all
had color-coded names. In days of yore, the ringback tone which
is the whirring sound you hear when you call somebody and their
phone is ringing came from the telephone office connected to
your friend's phone and the audio path for the call was open all
the way to his or her phone.

	This allowed for a whole bunch of mischief on either end
of the call. If you knew that a caller you did not want to talk
to had a certain background noise, for instance, you could build
a circuit with a DC blocking capacitor and clipper to hold down
the ring voltage and then monitor the audio on your phone line
without answering the call. You'd just hear whatever sounds the
caller's phone was picking up while between rings. The rings
just sound very loud over such a system.

	I knew one guy who did that because someone he didn't
want to talk to would call from a place where Muzak played all
the time. When the calls were awash with the sound of Muzak, he
knew not to pickup.

	As I understand it, a beige box had a capacitor to block
the DC on the line and if you could both transmit and receive
audio through the terminals of the beige box, you could carry on
a conversation, free of charge, between the rings.

	Another bit of mischief was sort of along the lines of
James Bond. You break in to some place you want to bug and place
a special device on a phone line that listens to the audio and
contains a filter of some kind tuned to a specific frequency
such as maybe 2 kilohertz or any audio frequency between 300 and
3000 HZ. Frequencies above or below this range may not make it
through the telephone network but 300-3000 is okay.

	You call the number of the line that got tapped and,
between rings, you send the tone that the filter responds to. If
you can do that before the first ring, your bugging device
answers the line silently and feeds audio back to you.

	If you are a miscreant and want to do that, there are a
number of ways you might get caught. It might ring immediately
when you finish the last digit which would make somebody maybe
answer the phone. If you're bugging the place and the victim
happens to pick up the phone to make a call, he may wonder why
he hears no dial tone and can hear sounds of some kind as if
somebody is already there. He may hear his own noises if the
microphone is near by.

	I actually read a description of such a bugging device
while taking a course about privacy issues so somebody really
did cook up one of these things. It wasn't me.

	The article was from the UK many years ago and was
published by something called the Scottish Office.

	In the present time, beige boxes and remotely-triggered
bugs might look interesting in a museum exhibit but they won't
work because most modern telephone exchanges feed the ringback
tone to the caller from his or her local exchange and the audio
path to the person being called is not established until that
person picks up and the line is said to supervise.

	I guess working in telecommunications for 25 years did
teach me a few things. Did I do any of that stuff? I actually
did briefly connect a sort of phone patch and listen to see what
the line sounded like back in the seventies. The #5 crossbar
switch we had here in Stillwater would faintly feed crackling
sounds and other operational noises down the line when it was
busy and they were kind of interesting to listen to for awhile.

	I also once did send a bit of 2600-HZ audio on the line
and it did drop a long-distance call.

	I am so glad I never tried any blue boxing, though,
because I later found out that many telephone offices in the
days of in-band switching had devices called "blue box
detectors" and I'll give you 3 guesses as to what they were for.
If they picked up those tones anywhere but where they should
exist, they got very interested in how they showed up on your
line.

	If you read, Exploding the Phone, there is a brief
mention of a student at Oklahoma State University who got in
trouble in the mid seventies. I have no idea who he was but that
was the same time I was here and, well, I think you get my
drift. That guy's got a Federal rap sheet and I don't.

Martin