quellish said:
*Listening* to your phone requires a warrant. Tracking what number calls what numbers does not.
http://w2.eff.org/Privacy/Surveillance/Carnivore/20000728_eff_house_carnivore.html
http://en.wikipedia.org/wiki/ECHELON
"The report concludes that, on the basis of information presented, ECHELON was capable of interception and content inspection of telephone calls, fax, e-mail and other data traffic globally through the interception of communication bearers including satellite transmission, public switched telephone networks (which once carried most Internet traffic) and microwave links."
As I understand it, the software reads your email and/or listens to your phone calls, and keeps on the lookout for keywords. In theory it's not supposed to keep records of regular messages, just when it finds something interesting.
It would clearly be illegal for a *human* to tap your phone and listen in without a warrant. But a robot? Apparently not.