Skype.com - Best Free Internet Telephony
Skype lets you call and speak to any other Skype user in the world from your computer for free. All you need is a microphone and a speaker.
website : http://www.skype.com/
You need Windows 2000, XP or Vista to run Skype. You can also use Skype to make calls to ordinary telephone numbers all over the world at a low cost. You can find more info on discount international phone calls using Skype at
http://www.skype.com/intl/en/allfeatures/callphones/.
The following languages are supported:
Czech (Čeština), Danish (Dansk), Dutch (Nederlands), English, Estonian (Eesi), French (Français), German (Deutsch), Hungarian (Magyar), Italian (Italiano), Norwegian (Norsk ), Polish (Polski), Portuguese (Português), Russian (Русский), Spanish, Swedish (Svenska), Turkish.