If you have a cell phone, a wireless device that allows you to have a conversation with anyone in the world, you have no protection against it being received by other than the person it's meant for. As far back as 1974, I had a police channel scanner that picked the then primitive cell phones. Put in in the air and it belongs to anyone. Nothing illegal about taking signals from the air. And if it is legal to collect, then it is legal to use against you. Only wire communication is protected. Phone taps of wire communications requires wire tap court authority.
It's not a matter with law not keeping up with technology. Technology has given criminals another way to communicate with no legal expectation of privacy. Stupid of criminals not to realize that. Speak to someone via Internet or cell phone, and you are speaking publically. Personally, I'm glad for that. I'm happy the gov't has the tools to intercept information that criminals voluntarily put upon the airways.
If they monitor my communications, that's okay. I have nothing to say that will lead to prosecution. I'm not plotting anything criminal. If I have an illicit affair with a fluzzy and I talk sex stuff with her on the Internet, I've committed no crime. (I say that as a matter legalities. Been married 43 years and never had such communication.) I'm just saying your private conversations are not private at all if you use your computer or cell phone.
If you want privacy, use a regular telephone or write a letter. Your emails and cell phone calls are legally retrievable.