Originally Posted by Ray Jones
Yeah. I'd like to go to the cinema and have some stupid watchdog people read all my messages and whatnot on the phone during that time.
In this case it's meant to be used in the case of finding out which phone number someone might call, say a terrorist during one of their operations, or effectively pinpoint someone and shut down their phone. I cannot think of anywhere phone reeading or blocking has actually been used but that's the basic idea. I think they tried to find the Oklaholma bombers by tracing their celluers.