VoIP technology basically converts your voice into a digital signal so that it may travel over the internet.  On the other end if you are calling a traditional land line the VoIP technology converts your electronic voice back into one compatible with regular phones. VoIP technology also gives you the flexibility of making calls from over more mediums then just a traditional telephone. You can actually make calls from:

• Your internet enabled PC to other PC's running VoIP programs.
• Your PC to a traditional land line.
• VoIP enabled phones.
• Traditional phones connected to a special Phone Adapter.