The Telecom Digest for December 12, 2010
Volume 29 : Issue 335 : "text" Format
Messages in this Issue:
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Date: Sat, 11 Dec 2010 04:10:30 -0500
From: Chris Hoaglin / Primary Rate <email@example.com>
Subject: Re: Question about an old scrambler phone
Ernie Donlin wrote:
> From: Ernest Donlin <firstname.lastname@example.org>
> To: email@example.com.
> Subject: Re: Question about an old scrambler phone
> Message-ID: <AANLkTikNo4yk2IrcNuKp_F8QRugnedkZuknL1PEFju-E@mail.gmail.com>
> On Wed, Dec 08, 2010 at 06:38:59AM -0600, Robert Bonomi wrote:
>> > In article <AANLkTikNo4yk3iRENuKp_f4QRTgnedkZuknL1PEFju-E@mail.gmail.com>,
>> > Ernest Donlin <firstname.lastname@example.org> wrote:
>>> > >(moderator please change my email address so spammers can't use it.)
>>> > >
>>> > >I've got an odd sort of a question for your group.
>>> > >
>>> > >When I was a kid, my friend's dad had a phone in his house that he told me
>>> > >was a "scrambler". It was a regular telephone, mounted on a metal
>>> > >base, with an AC cord for the base. The base had just two vacuum tubes in
>>> > >it, and a couple of transformers. It didn't look like much, but my friend
>>> > >said his dad used it to make scrambled phone calls to his reserve unit.
>>> > >
>>> > >Has anyone ever seen anything like that? I never knew if he was yanking my
>>> > >chain or not.
>> > One of the simplest forms of a 'scrambler' simply frequency-inverted the
>> > audio input. basically, use the audio to AM modulate a circa 4kHz 'carrier',
>> > and send only the the lower sideband over the wires..
>> > Conveniently, you can 'unscramble' the signal by doing exactly the same
>> > thing to the 'scrambled' signal.
>> > Necessary components are: 1) an oscillator, 2) a modulator, 3) a low-pass
>> > filter. That's two tubes, and an inductor with a couple of capacitors,
>> > plus a multi-tap (filament and B+) power transformer to run it all.
>> > Sounds real close to what your friend's dad had. <grin>>
>> > Now, to answer the actual question you asked: "No, I've never actually
>> > seen one of them myself." I only know "of" such devices, having read
>> > about, seen schematics in books, etc.
> Thanks, that's nice to know. I didn't think my friend would go to all
> that trouble to put a box and tubes, etc. on the bottom of a phone,
> but it still seemed so simple a circuit that I couldn't quite believe
> it would work.
> Now, I'm curious: is that kind of scrambling still possible? It seems
> like it would be a neat way to keep the kids from picking up the phone
> when I want to gab with the wife. I'm not going to build one, but I
> wonder if there's anything I can buy online?
> Thanks for helping.
> -- Ernie Donlin
I'm somewhat amused that anybody would consider their conversations
with their reserve unit sensitive enough to require speech scrambling.
More recently, speech inversion has been used in some analog cordless
phones, various radio systems, and in central office remote line testing
equipment to allow line monitoring while maintaining some level of
privacy. The Harris DATU from the 90's is one example, and I'm sure
there are others.
>From an old hacker-zine article about the DATU's:
"AUDIO MONITOR - The subscriber line may be monitored for up to 10
minutes, after which time the DATU disconnects from the No-Test trunk.
Audio Monitor may be used on either busy or idle lines. Traffic on a
busy line will be audible but unintelligible. The Audio Monitor Mode may
be exited before the end of the 10 minute period by selecting an
appropriate test function."
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Date: Sat, 11 Dec 2010 10:40:35 -0800 (PST)
From: Lisa or Jeff <email@example.com>
Subject: Re: Question about an old scrambler phone
On Dec 11, 4:10 am, Chris Hoaglin / Primary Rate
> More recently, speech inversion has been used in some analog cordless
> phones, various radio systems, and in central office remote line testing
> equipment to allow line monitoring while maintaining some level of
> privacy. The Harris DATU from the 90's is one example, and I'm sure
> there are others.
A long time standard feature in telephone service is the ability of
the operator to break into ongoing calls to announce an emergency
call. (Now they charge a steep fee to do that). Before doing so,
they listen in to ensure the line is actually 'busy talking' and not
merely off hook or our of order. (Verifying a busy line is a fee now,
Some time ago Bell Labs Record reported on a device that would allow
operators to confirm the line was in use with a conversation without
the operator being able to listen to the conversation. The device
would scramble the conversation so the operator would hear
To me, this seemed like overkill. Bell operators worked under strict
quotas and supervision and they wouldn't have time to sit there and
listen in to a conversation, especially with a subscriber on the line
waiting for a result. Plus, I dare say the vast majority of telephone
conversations are rather boring.
Anyway, I have no idea if this device was ever rolled out, or if so,
how widely it was used.
Date: Sat, 11 Dec 2010 19:19:27 -0500
From: Monty Solomon <firstname.lastname@example.org>
Subject: Angry Birds, Flocking to Cellphones Everywhere
Angry Birds, Flocking to Cellphones Everywhere
By JENNA WORTHAM
December 11, 2010
It sounds like a tough sell: a game that involves catapulting birds
at elaborate fortresses constructed by evil pigs.
But Angry Birds, a hit game by Rovio, a small Finnish company, is one
of the unlikeliest pop-culture crazes of the year - and perhaps the
first to make the leap from cellphone screens to the mainstream.
Angry Birds, in which the birds seek revenge on the egg-stealing
pigs, is meant to be easily played in the checkout line and during
other short windows of downtime - but some players have trouble
stopping. Rovio says people around the world rack up 200 million
minutes of game play each day. (Put another way, that is 16
human-years of bird-throwing every hour.)
The game has inspired parodies, homages and fervent testimonials.
Homemade Angry Birds costumes were big hits on Halloween. Conan
O'Brien demonstrated the game in a YouTube video promoting his new
show, and a sketch from an Israeli TV show about a birds-and-pigs
peace treaty was popular online. Justin Bieber and other celebrities
have professed their love of Angry Birds on social networks.
Games like Angry Birds are reaching a wide audience of players who
might never consider buying an Xbox or PlayStation, but are now
carrying sophisticated game machines in their pockets - smartphones.
Software developers, eager to become the next Rovio, are creating
so-called casual games for this crowd, games that are easy to learn
and hard to stop playing.
The trajectory of Angry Birds also suggests a larger shift in
entertainment and in the kinds of brands that can win wide
popularity. And unlike many of the best-known console video games -
like the classic Super Mario Bros. from Nintendo or the latest in the
Call of Duty series, from Activision - cellphone games like Angry
Birds are often made by small companies and catch on by word of mouth.
Date: Sat, 11 Dec 2010 20:46:09 -0600
From: John Mayson <email@example.com>
Subject: Re: Angry Birds, Flocking to Cellphones Everywhere
I am 41 years old. I have not been a video game fan since I was about
14 or so. I have no games on my laptop. I have only a couple of
games on my phone and iPod Touch. My son suggested I install Angry
Birds on my phone. I absolutely cannot put it down. I cannot explain
the appeal. I am probably the least likely of anyone to get hooked on
it, but I have.
John Mayson <firstname.lastname@example.org>
Austin, Texas, USA
***** Moderator's Note *****
When I was ten years old
I remember thinking how cool it would be
When we were going on an eight-hour drive
If I could just watch TV
And I'd have given anything
To have my own Pac-Man game at home
I used to have to get a ride down to the arcade
Now I've got it on my phone
Hey, glory, glory, hallelujah
Welcome to the future
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End of The Telecom Digest (4 messages)