When did cordless telephones come out?

[ChrisW6ATV]

I think I bought my first cordless phone in 1985. It was a Panasonic that used the then-"new and improved" 46 and 49 MHz bands for talk and receive. Previous models had used 1.7 and 49 MHz for the two audio channels. None of these phones were ever expected to work beyond your own home, maybe 100 feet (30 meters) or so.

As late as 1991-1992, I tuned my wide-coverage, multi-mode "shortwave" (HF) ham radio receiver into the 1.7-1.8 MHz range and set it to FM mode, and I heard a neighbor's phone call, so I knew they were using an early cordless phone. That was right in the era when cell phones were still almost all analog and the FCC (here in the USA) had banned radio receiver manufacturers from selling any radios that could receive the cell-phone bands. Those bands then were 825-845 MHz and 870-890 MHz, later expanded to 824-849 and 869-894.

In the late 1990s, I bought a Sony cordless phone that worked in the 900 MHz band, and it had -amazing- range. It was reliable to use almost a block away! (Over 500 feet or 150 meters.) I wanted to try boosting it even more by connecting an external outdoor antenna to it, but I never did try. Since I still have the phone here somwhere and a couple of good 900 MHz antennas, I should still do it...

[Robert Gift]

... That was right in the era when cell phones were still almost all analog and the FCC (here in the USA) had banned radio receiver manufacturers from selling any radios that could receive the cell-phone bands. Those bands then were 825-845 MHz and 870-890 MHz, later expanded to 824-849 and 869-894. ...

I would have changed some components in my receiver to monitor those frequencies.
Would I have heard anything?

[countryman]

That's above the UHF TV band. It's hard to modify a receiver in that range, unless it is designed for it from factory and "banned" bands are only excluded by software or programmable jumpers (We had that here in Germany, too. It was legal to own but illegal to use radios without official approval mark.)
All the low band cordless phones were analog and usually easy to overhear. The first UHF ones were also analog, I guess they used FM and no encryption? Later ones are all digitally encrypted.

[ChrisW6ATV]

A nice, high-end radio scanner was released by Radio Shack (model PRO-2004) right when the ban went into effect in the USA. It had those 800-MHz bands blocked, but they could be restored with a minor modification to the radio. So, of course I did that, maybe more for the "forbidden fruit" aspect than anything. I listened to the cell-phone bands a few times, but it was mostly just boring, routine conversations. Businesses dispatching technicians, truck drivers reporting their arrival times, sometimes a "Hi honey, I am on my way.","OK, can you get some milk?"-type call.

[SUnset2]

When the upper UHF TV frequencies (806-890 MHz) were re-allocated to cellular telephone service in the 1980s, it was possible to accidentally pick up one side of analog cellular conversations when adjusting your UHF tuner between channels 70 and 83. (The older UHF tuners had continuous tuning over the whole band with no presets).