From the Desk of David Pogue - Take Back the Beep Campaign - NYTimes.com

... we're PAYING for these messages. These little 15-second waits add up--bigtime. If Verizon's 70 million customers leave or check messages twice a weekday, Verizon rakes in about $620 million a year. That's your money. And your time: three hours of your time a year, just sitting there listening to the same message over and over again every year.

In 2007, I spoke at an international cellular conference in Italy. The big buzzword was ARPU--Average Revenue Per User. The seminars all had titles like, "Maximizing ARPU In a Digital Age." And yes, several attendees (cell executives) admitted to me, point-blank, that the voicemail instructions exist primarily to make you use up airtime, thereby maximizing ARPU.