Skype allows the creation of video conference calls. Skype is available for Microsoft Windows, Macintosh, or Linux, as well as Android, Blackberry, and both Apple and Windows smartphones and tablets.[16] Skype is based on a freemium model. Much of the service is free, but Skype Credit or a subscription is required to call a landline or a mobile phone number. At the end of 2010, there were over 660 million worldwide users, with over 300 million estimated active each month as of August 2015.[17] At one point in February 2012, there were thirty four million users concurrently online on Skype.First released in August 2003, Skype was created by the Swede Niklas Zennström and the Dane Janus Friis, in cooperation with Ahti Heinla, Priit Kasesalu, and Jaan Tallinn, Estonians who developed the backend that was also used in the music-sharing application Kazaa.[19] In September 2005, eBay acquired Skype for $2.6 billion.[20] In September 2009,[21] Silver Lake, Andreessen Horowitz and the Canada Pension Plan Investment Board announced the acquisition of 65% of Skype for $1.9 billion from eBay, which attributed to the enterprise a market value of $2.92 billion. Microsoft bought Skype in May 2011 for $8.5 billion. Its Skype division headquarters are in Luxembourg, but most of the development team and 44% of all the division's employees are still situated in Tallinn and Tartu, Estonia.kype allows users to communicate over the Internet by voice using a microphone, by video by using a webcam, as well as with instant messaging. Skype-to-Skype calls to other users are free of charge, while calls to landline telephones and mobile phones (over traditional telephone networks) are charged via a debit-based user account system called Skype Credit. Some network administrators have banned Skype on corporate, government, home, and education networks,[25] citing such reasons as inappropriate usage of resources, excessive bandwidth usage, and security concerns.
Registered users of Skype are identified by a unique Skype Name and may be listed in the Skype directory.[42] Skype allows these registered users to communicate through both instant messaging and voice chat. Voice chat allows telephone calls between pairs of users and conference calling and uses a proprietary audio codec. Skype's text chat client allows group chats, emoticons, storing chat history, and editing of previous messages. Offline messages were implemented in a beta of version 5 but removed after a few weeks without notification. The usual features familiar to instant messaging users—user profiles, online status indicators, and so on—are also included.The Online Number, a.k.a. SkypeIn, service allows Skype users to receive calls on their computers dialed by conventional phone subscribers to a local Skype phone number; local numbers are available for Australia, Belgium, Brazil, Chile, Colombia, Denmark, the Dominican Republic, Estonia, Finland, France, Germany, Hong Kong, Hungary, Ireland, Japan, Mexico, Nepal, New Zealand, Poland, Romania, South Africa, South Korea, Sweden, Switzerland, Turkey, the Netherlands, the United Kingdom, and the United States.[43][44] A Skype user can have local numbers in any of these countries, with calls to the number charged at the same rate as calls to fixed lines in the country. The countries on this growing list are referred to collectively as the SkypeIn Countries.Skype does not provide the ability to call emergency numbers, such as 112 in Europe, 911 in North America, or 100 in India and Nepal.[47] However, as of December 2012, there is limited support for emergency calls in the United Kingdom, Australia, Denmark, and Finland.[48] The U.S. Federal Communications Commission (FCC) has ruled that, for the purposes of section 255 of the Telecommunications Act, Skype is not an "interconnected VoIP provider".[49] As a result, the U.S. National Emergency Number Association recommends that all VoIP users have an analog line available as a backup.Skype also offers a Skype Wi-Fi Phone, which is a wireless mobile phone that allows users to make Skype calls, using a wireless Internet connection. The Skype Wi-Fi Phone has an on-screen menu that lets Skype users see who is online and available to talk, similar to what is seen on a PC. It can also be used to talk with non-Skype users. SkypeOut minutes can be used to call any phone for a low price and no monthly fee. The Skype Wi-Fi phone does not contain a web browser and so can not access hotspots that require web-based login or authentication.Skype uses a proprietary Internet telephony (VoIP) network called the Skype protocol. The protocol has not been made publicly available by Skype, and official applications using the protocol are closed-source. Part of the Skype technology relies on the Global Index P2P protocol belonging to the Joltid Ltd. corporation. The main difference between Skype and standard VoIP clients is that Skype operates on a peer-to-peer model (originally based on the Kazaa software[98]), rather than the more usual client–server model (note that the very popular Session Initiation Protocol (SIP) model of VoIP is also peer-to-peer, but implementation generally requires registration with a server, as does Skype.
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