WireChatter.com

How many times have you waited at your desk for an important phone call? Or made a mad dash across the office when you heard your desktop phone ringing? Would you like to be able to receive calls to your business number when you’re away from the office, without having to lug around your laptop [...]

Peter Cox(?) a security consultant specializing in VoIP security has a great Podcast primer on VoIP security examples. He states that there are really three categories of VoIP Security Threats:

IP level Threats – shared with the web and email and others, common knowledge to many people already
Protocol and application specific threats, based on the way [...]