In Part 1 of this opus, I (hopefully) painted a scary picture of how easy it is to eavesdrop on VoIP traffic. So what can you to protect your own VoIP traffic? Let's take a look at some of your options.
-- Use Skype
Skype is famous for its excellent call quality and reliability. Its call security is pretty good, and is used on all Skype services—VoIP calls, text chat, and video and file transfers. Skype uses a digital certificate authority and signed certificates, peer authentication, and strong encryption.
-- ZRTP encrypts all VoIP
PGP is the most widely used e-mail encryption software. It now exists in two main forms: a commercial implementation maintained by the PGP Corp., and the free software version, GNU Privacy Guard (GPG). (more)