Imagine showing up for work and discovering you've got 457 voice-mail messages. Almost all of them are telemarketing junk -- but somewhere in the mess, there's probably a few important voice-mails from actual co-workers. How long would it take you to listen to them? That may soon become a reality for many people, because of "voice over IP" phone numbers. Why? Well, as you probably know, VOIP routes phone calls over the Internet as packets of data, instead of using normal phone switches. That means VOIP phone companies can offer steep discounts on long distance. Indeed, that's why many corporations are turning to VOIP -- to cut costs! Even better, because the phone number is entirely, VOIP can do some cool tricks: Your number can be directed to any VOIP number in the world, so it can travel with you. And you can access your voice mail by checking a...