content: Somehow the US gov thinks stealing text is legal, but stealing audio is non-exactly-legal-without-FISA-warrant.  Might not be so much the legality, but the efficiency of transmitting a text doc vs .wav or .mp3 file. Less bandwith footprint and easier to index. Dunno. I used to work at a place that recorded every phone call. One guy was having bad relationship issue and would talk to wife on taped line. People upstairs would seek those recordings and listen because of the juicy fireworks.