They look like they'be been around that long...and they look unassuming enough to the uneducated eye, as well. So amazing what a little box can hear.
Would love to learn more about their use historically and about them in general if you decide to post on them. I've done quite a bit of reading but would enjoy reading a post from you on the subject.
I had a look into it. There really is too much to cover. Everything from computers and mobile phones to IoT technology like smart gas/electricity meters and TVs!
It's very scary, especially when you consider the wealth of anti-technology agencies have at their disposal now. Plus most of it is mobile too which make it even more haunting.
I'll be honest, I only know that from an early 90s movie about a hacker. The technology back then would simulate a cellphone site by overpowering the signal - which still works and is also how TV broadcasts used to be hacked by teenagers - but I can't say much about the older versions. But I think what I'll do is write a big article up tomorrow about all the different technologies that are used in our day and age "to fight crime". It sounds like it would be interesting. Good idea!