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!