Echelon
Computer system operated by NSA for purposes of locating possible threats through scanning of electronic communications.
The system takes random samplings of all communication types including voice, and scans them for keywords, such as anthrax, in most languages. If it finds one, whatever uplink you used will be listened to more often, and common occurances of keywords may promt the system to alert a human operator.

Unless you are talkin about that sorta stuff all the time, you'll never even be noticed.