Brendon Macaraeg writes:

Cpunks:

While shopping for a new phone recently, I came across two models (Toshiba and Uniden I believe) that have buttons to "privatize" you conversations. These were on no-cord models.

I have one of these, a Panasonic "Secure Guard" cordless. It was on sale, I couldn't resist. :-) It's a 46mhz analog model, newer phones use frequencies in the 900mhz range and/or digital encoding. The 900mhz range is one of those 'blocked' in most newer radio scanners, this is required by law as of a few years ago. Many scanners can have some or all of the locked-out ranges restored by suitable modification (i.e. removing a resistor). Many of these mods are posted on the net.

Does anyone have any idea on what these actually do? Can the phones change the frequency the call is on randomly so people can't tune into it?

The Panasonic I have doesn't change frequencies during the call by itself, although you can do that by pressing a button. The "secure" feature does some sort of analog frequency-diddling to make most of the sound transmitted between the phone and base unit unintelligable. I'm not a hardware type but I expect that this isn't very hard to 'crack' given a bit of equipment. I'm sure most HAM hobbiests could do so. It only keeps your conversations somewhat safe from the local snoops with scanners. While most speech comes out pretty good, you can't have the 'secure' feature on when you're attempting to navgate phonemail systems... it messes up the DTMF tones just enough to make then unrecognizable to many phonemail systems.

I know cellulars offer something similar.

Yea, that's more secure although if I remember right, nowhere near unbreakable. Why, then drug dealers and terrorists could make phone calls and our great and wonderful law enforcement personell would not be able to listen in on the perps. Wouldn't want that now, would we?

Personally, I would never put much faith into something of this sort.

Well, it's not "secure" but it's somewhat better than nothing. -- Eric Murray ericm@lne.com ericm@motorcycle.com http://www.lne.com/ericm PGP keyid:E03F65E5 fingerprint:50 B0 A2 4C 7D 86 FC 03 92 E8 AC E6 7E 27 29 AF