>Does anyone know the tecnical name for the voice scrambling systems
 >used in cordless phones and 2 way radio communications?  How does it
 >work and how safe am I using it in my business?  No hunches please, I
 >need info from someone who really knows this technology.
Most of the 46/49MHz models use "voice inversion." The way it works is that 
both the handset and base unit contain a cicuit which basically turns the 
audio "up-sidedown." Each unit (base and handset) has its inversion circuit 
set to the same "reference" frequency; say for example, 1000Hz. Any audio 
which enters the circuit above 1000Hz would  come out that much below 1000Hz 
and vice-versa. In other words, if audio was entering at 1100Hz, it would 
come out as 900Hz, and audio coming in at, say, 800Hz would come out as 
1200Hz. Since both the base unit and the handset have the inversion 
circuitry, the signal is inverted twice. Two negatives make a positive 
(unless you're talking about ebonics, but that's a whole different story). 
B-)  When you tune in one of these signals on your scanner, it's only been 
inverted ONCE, (by the base unit), and it sounds like some kind of alien 
voice. You can buy inversion type descambler kits from a number of sources. 
Probably your best bet would be Ramsey. (Call 1-800-446-2295 for a catalog.) 
As for how safe you are using this type of technology, as I said, descrambler 
kits are readily availble. So it's not the exactly the safest form of 
telephone security, although very few "casual" scanner listeners care to go 
to all the trouble of building a desrambler.
Disclaimer: Using descramblers is against the law, so please ignore 
everything I just said. B-)
As for the 900Mhz phones, most of those use digital scrambling, and I have no 
idea how it works! I'm not aware of ANYONE who's been able to descramble this 
stuff. My wife and I own one of the digital 900MHz phones, and even though I 
can find the operating frequencies with my frequency counter, when I try to 
tune them in on my scanner, I can't even detect a carrier! If you need voice 
security, I would recommend one of these. If you can get one of the 
"spread-spectrum" phones, that would be even better, since they are 
constantly changing channels at a very rapid pace. There's no way a scanner 
can keep up with them!
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