Skype (IPA pronunciation: /skaɪp/, rhymes with type) is a proprietary peer-to-peer Internet telephony (VoIP) network, founded by Niklas Zennström and Janus Friis, the creators of KaZaA and competing against established open VoIP protocols like SIP, IAX, or H.323. The Skype Group is headquartered in Luxembourg with offices also in London and Tallinn. The system has a reputation for working across different types of network connections (including firewalls and NAT) because voice packets are routed by the combined users of the free desktop software application. Skype users can speak to other Skype users for free. Skype also has paid services allowing users to call traditional telephone numbers (SkypeOut), receive calls from traditional phones (SkypeIn), and receive voicemail messages.
In September 2005, in a deal generally criticised by many as overpriced, eBay acquired the company for $US 2.6 billion in cash and stock, plus an additional 1.5 billion in rewards if goals are met by 2008.
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wikiOfficial Skype Website