Some of those brands like Uniden and Casio were such garbage. I sold them by the thousands at the Northridge JCPenney, and took back nearly as many in returns. Anything that wasn't a phone company brand was basically junk.
Some of those brands like Uniden and Casio were such garbage.
Well, that depends on the model.
Uniden's second generation 900 MHz DSS phones were the apex of cordless phone design. Not only can't you hear them with a scanner, but you can't even find them with a frequency counter! They frequency-hopping is so rapid that the counter can't latch onto it, and even IF a scanner could, all you'd here would be "digital noise" (and then, only a portion of it -- whatever one of the numerous "hop-stops" you landed on).
They're probably good for two miles or so if you've got the base on an upstairs location and flat land. Here, with the base on the ground floor, and hilly land, with buildings blocking the signal (as well as tons of rock and dirt in the hills), we get about a half mile.
The newer phones, from what I've heard -- the "gigahertz" models, not only send half the duplex circuit in "cleartext" FM, but, due to the nature of microwave propagation, have much shorter range, and don't go through walls nearly as well.
To give something of a benchmark, our Uniden phone has more range than our "old" Cherokee FRS radios. (They were the only FRS radios that gave an actual half-watt ERP. The actual transmitter output to the antenna was on the order of .8 watt. Legal, since the FCC regulates ERP. Everyone else went with .5 watt output, and the ERP out of the little untuned antenna was much less. They weren't on the market all that long, probably because they used a standard UHF connection for the antenna, which was not legal. FRS radios have to have permanently attached antennas.)
Anyway, there were indeed some very good cordless phones available (still are, on the used market), with really amazing range, and true privacy via two-way digital spread spectrum.