Skype

Skype is a peer-to-peer internet telephony network, founded by Niklas Zennström and Janus Friis, the creators of KaZaA. However, unlike its older sibling, Skype is free of spyware and adware. Skype is proprietary software, but is freely available for Microsoft Windows (Windows 2000, Windows XP and Windows CE (Pocket PC 2003)), Mac OS X and GNU/Linux. It is not compliant with the SIP protocol (see ).

Unlike some other VoIP programs, Skype intelligently routes calls between users. It will even try to find a way through most firewalls. It is designed to "just work".