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From: jta@hydra.jpl.nasa.gov (Jon T. Adams)
Newsgroups: comp.dcom.telecom
Subject: Re: AT&T Cordless Phones, Security, Flexible Antennas
Message-ID: <16537@accuvax.nwu.edu>
Date: 29 Jan 91 21:13:12 GMT
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X-Telecom-Digest: Volume 11, Issue 79, Message 3 of 12


Somebody named "Tiny Bubbles" queries:

> 1.  Are flexible antennas any good?  They sell them for ten bucks or
>     so at the local discount store (genuine AT&T), but they're pretty
>     short compared to the "whip" that comes with it.  Do they work as
>     well as the whip?  (Too bad they can't retract.)

For the most part, the current rash of portable phones that use the
46MHz/ 49MHz spectrum will not work quite as well using a rubber duck.
Capture area is what generally makes an antenna and using a physically
smaller antenna does reduce the capture area.  However, since you are
dealing with a hand-held radio which is a decidedly non-optimal
environment for RF propagation especially at around 50MHz, you will be
happier choosing personal convenience rather than efficiency.  In
other words, if I was regularly breaking the metal whip antennas (or
had an urchin that did) I would opt for the flexible antenna.  Also
consider moving the base unit to a better location, higher up (get it
off the floor), etc.

> 2.  Without divulging anything nasty, how secure is the security code?
>     Are voice transmissions scrambled by the key, or is it just the 
>     dialing codes?  I ask because recent rulings say that monitoring
>     a radio broadcast from a cordless phone is not a "wiretap," and I
>     wonder if my phone is safe.  That's a big consideration for me, and
>     it's one of the reasons I buy AT&T cordless phones.

The security codes vary in their sophistication; but all concern
themselves only with protection from some other person using your
phone line and/or your handset ringing when someone else locally
receives a call.  None do any kind of voice encryption.

Nothing you say on a portable telephone (different only by politics
from a "cellular" telephone) is legally protected from eavesdropping.
In fact, anyone with a 46 to 49MHz radio receiver / scanner (available
at Radio Shack and anywhere else) can pick up your conversations.  The
police can enter anything heard there as evidence in court.  But it's
fairly boring eavesdropping, at least in MY neighborhood...

Eventually, if enough people complain that their "rights" are being
violated by this loophole, well maybe Congress'll just pass another
law, forbidding anyone from listening, just like up in the cellular
telephone spectrum.  Or, with the same likelihood of a snowball
lasting fifteen minutes in Hell, maybe some smart manufacturer will
come out with a great new phone and some reasonable encryption system
using spread-spectrum stuff and will make this fact pointedly known
through worldwide advertising.  There's still room for
entreprenuers.

But they are darned handy things to have.  Plantronics makes one (or
more likely, MADE one, since DAK now sells it for 59.95) that clips on
your belt, has a tone pad for dialout, and a featherlight earphone/mic
that just fits in your ear.  Great for when you're working around the
house.

Have fun!


jon