the times investigates ghost calls, those phone calls where you pick up and get no answer. most of the time (apart from actual stalkers and ghosts), these come from predictive dialing machines that telemarketing companies deploy to relay their messages. the hangup occurs when the machine succesfully connects to a person, but there are no free telemarketers available, thus the fcc requires that the dialer hang up. lovely.
technology: battling ghost calls, that telemarketing annoyance, by peter wayner