Talk is cheap…if you are using IP Telephony! IP Telephony is one of the hottest emerging technologies, and it is attracting the attention of the biggest players on the Internet. Skype was purchased by eBay, Google offers GoogleTalk, and Yahoo! offers Yahoo! Messenger with Voice. These services allow users to call anyone worldwide via their PCs for free . They also offer various premium services, including calling from your PC to traditional phones.

We begin our peak inside Internet telephony with our Skype Resource Center. You’ll find information about Skype, its features, and software and accessories you can use with it. You’ll also find links to some of the industry and blogger buzz about Skype.

http://www.skype.com/
With Skype you can make free calls over the Internet. Skype – the whole world can talk for free. 
Skype is a free, peer-to-peer (P2P) software application. Use Skype with a PC headset, or a PC microphone and speakers. Soon you’ll be able to use Skype on mobile devices and handsets.