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Skype

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Alexandra B

on 14 October 2013

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Transcript of Skype

Skype is a voice-over-Internet Protocol service and software application that allows its users to communicate with each other by messaging, video and audio calling.

Phone calls may be placed to recipients on the traditional telephone networks but that is a paid service. Calls to other users within the Skype service are free of charge, while calls to landline telephones and mobile phones are charged via a debit-based user account system. Skype has also become popular for its additional features, including file transfer, and videoconferencing.

Skype has 663 million registered users as of September 2011. As of 05 March 2012, the record for the most simultaneous online users on skype was broken with 35 million simultaneous users.

The network is operated by Microsoft, which has its Skype division headquarters in Luxembourg.
History
Skype was founded in 2003 by Janus Friis from Denmark and Niklas Zennström from Sweden.

The Skype software was developed by Estonians Ahti Heinla, Priit Kasesalu, and Jaan Tallinn, who together with Janus and Niklas were also behind the peer-to-peer file sharing software Kazaa.

In August 2003, the first public version was released.

On 10 May 2011, Microsoft Corporation agreed to buy Skype Communications, for US$8.5 billion. The company is now a division of Microsoft, and Microsoft acquired all of the company's technologies with the purchase.

This was completed on 13 October 2011.
What is Skype?

Some devices are made to work with Skype by talking to a desktop Skype client or by embedding Skype software into the device. These are usually either tethered to a PC, or have a built-in Wi-Fi client to allow calling from Wi-Fi hotspots.
• Computers with Mac, Windows, or Linux operating systems.
• Play Station Portable (PSP)
• Tablet Devices (excluding Blackberry Playbook)
• iPads:. On 2 August 2011, Skype officially released an iPad app named 'Skype for iPad' which allows the user to have video calls using iPad 2's front and back cameras. The original iPad is also allowed to make calls but only voice calls, The other person on the other side can make a video call if they have a camera, and the original iPad can only receive the video but not send.
• iPhones
• Mobile devices running Windows Mobile
• Many Android 3G Smartphones
• Some Tv’s: which have wi-fi capabilities and a webcam hooked up can have Skype. Until November 2010, only certain Samsung and Panasonic TVs offered Skype video service.
Devices that support Skype
How Skype Works
Protocol
A protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications. A protocol may have a formal description.Protocols may include signaling, authentication and error detection and correction capabilities.

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.
Codecs
***What is a Codec? Software or device that controls a digital media file (such as a song or a video), for example encrypting, compressing and/or decompressing the data in it. Media players use codecs to play back videos and audio files like MP3. To explain with a simple analogy, codecs are like translators. They work on some specific data and convert it into something that’s easily understandable by the different media players that are there on our computer.**

Audio: G.729 and SVOPC. Skype added a Skype-created codec called SILK to Skype 4.0 for Windows and other Skype clients. SILK is intended to be "lightweight and embeddable"

Video: VP7 is used for versions prior to Skype 5.5. As of version 5.7 VP8 is used for both group and one on one standard definition video chat and H264 is used for 720p and 1080p high definition group and one on one video chat.
***What is a client? A client is the requesting program or user in a client/server relationship. For example, the user of a Web browser is effectively making client requests for pages from servers all over the Web. The browser itself is a client in its relationship with the computer that is getting and returning the requested HTML file. The computer handling the request and sending back the HTML file is a server.***

Skype clients are available for Microsoft Windows (2000, XP, Vista, 7, Mobile), iOS (iPad, iPhone, iPod Touch), Mac OS X (Intel, PPC), Symbian S60, Sony PlayStation Portable (PSP), Linux (includes Android, Maemo), and for 2010 TV models from LG, Panasonic, and Samsung, but these TVs need a special webcam.
Client
VoIP
VoIP stands for voice over Internet protocol and often pronounced "voyp" — is a new technology that will improve the way we communicate. It has emerged as a substitute for century old telephones. Ordinary telephones send and receive analogue signals but VoIP converts our analogue signals to digital packets. While after converting them in to digital signals, these are divided/broken in to small packets before they are given to internet. This is exactly how computer send data to each other on internet. Each packet contains its destination address and instructions on how to bring it back to original form. These packets are transported to their destination via internet. At destination VoIP gateway does the reverse process and these digital packets are brought back into analogue form and given to telephone set.
Cost
Skype is Free!
Skype is free to download and many features are absolutely free to use between Skype users all around the world. The free service of Skype offers unlimited Skype to Skype user messaging, audio and video calls, screen sharing, and file sharing. Still want more? For a low cost Skype offers more useful features.
Or pay a little . . .
VoIP owes its versatility to another fantastic technology, the Internet. Instead of sending signals via a PSTN (publically switched telephone) network, be it analog or digital, a VoIP application usually uses SIP to create data packets, and sends them on the same network you use for email and web surfing.
The Session Initiation Protocol (SIP) is a signaling protocol used for controlling communication sessions such as voice and video calls over Internet Protocol (IP). The protocol can be used for creating, modifying and terminating two-party or multiparty sessions. Sessions may consist of one or several media streams including video conferencing, streaming multimedia distribution, instant messaging, presence information, file transfer and online games.
By using data packets, the technology can be used to carry more than the standard mono voice your old telephone does; VoIP can carry text, images, live video and high quality stereo sound as well as ‘screen sharing’, depending on the speed and reliability of your internet connection.
The journey starts at the receiver, which can range from specialized hardware appliances like the ‘Skype-phones’ and Cisco VoIP phones to software applications installed on other mobile terminals or computers. All devices must be capable to send and receive data packets via a specialized network (an IPv4 network). Your voice is captured and transcoded from the analog format that the microphone captures, into a digital format, then passed on to a compressor that minimizes the size of the audio stream enabling transfer on slow connections
The audio stream is then divided into small pieces, each small enough to fit in a packet, which is stamped with the destination address and sent through the network. Since VoIP uses SIP as the means to spread, it is inherently prone to its negative sides, which are quite a few, since it was never engineered to support live conversations; VoIP is susceptible to stutter and latency.
The receiving end must reconstruct the packets sequentially for ideal reproduction, which does not happen on most public networks, which are prone to congestions during peak hours. Latency and packet loss can render the receiving end to be unable to reconstruct the complete audio stream resulting in blank audio space for short periods.
Although it’s much more versatile than traditional PSTN communications, VoIP has been criticized by many as being unreliable, especially in emergency situations where electrical power is absent or intermittent. Supporting hardware such as wireless routers need electricity at all times to function properly. Most people in the United States still keep a landline for emergency situations, which can provide enough direct current to power most analog phones without any additional power sources.
Emergency services have strongly objected to the use of VoIP for emergency calls due to the inability to locate the caller within a reasonable area. For example, a user connected to the office VPN network would appear to be in the server building instead of the real location.
In ideal situations, where a broadband connection and electricity are available at all times, VoIP technology provides an incredibly cheap and comprehensive way to communicate, mitigating roaming charges that traditional service providers require for long distance calls. Many consumer VoIP service providers offer free calls within their user base of Internet connected clients (computer-computer, skype-phones and other terminals). They also offer to interconnect with traditional networks for low fees. Some, like Skype, even offer standard telephone numbers than can be dialed from any telephone and which redirect to your Skype enabled device.
Now . . . .
A demonstration on how to download and use Skype
Features
Audio Calling
Skype to Skype Calling
Talk to anyone else who has Skype, anywhere in the world, for FREE.
Skype To Go numbers
Call international numbers from any phone at Skype's great rates. Save on calls abroad. Make low-cost international calls from any mobile or landline - without having to sign into Skype. Your benefits . . .
• Call abroad when away from your computer.
• Dial from any phone - mobile or landline.
• No download or installation required.
• No internet connection or data plan required.
• Enjoy Skype's great rates to call mobiles and landlines.
Conference calls
Talk to more people on one call – for free if everyone's got Skype. Add people on phones using Skype Credit or at no extra cost with a subscription

Online Number
Your friends call a number and you pick up on Skype wherever you are in the world – $18 for 3 months or a whole year for just $60. The number that reaches you – wherever you are An Online Number (also called Skype number) is a number anyone can call you on from their mobile or landline - and you answer on Skype, no matter where you are. And with every Online Number you also get voicemail included. Then when family and friends call your Online Number and you're unavailable, they simply leave a message which you can listen to the next time you sign in to Skype.
Skype to Landline Phones and Mobiles
Call mobile or landlines, anywhere in the world, from just 2.3 cents per minute with a Skype Credit or even cheaper with a subscription.
Video Calling
Video Calling on Skype
Talk face to face with live video for FREE!
Group Video Calling
Talk Face to face with a group of people anywhere in the world. At least one person on the call needs Skype Premium or a group video subscription from Skype Manager. For everyone on the call to see video, each person needs a webcam, a broadband connection and Skype 5.0 or Skype business version. Group video calls can be between three or more people (up to a maximum of 10). For the best quality, we recommend calls with up to five people.
Screen Sharing
Share your screen with anyone on Skype for FREE or share with a group with Skype Premium. It is a great way to show files, pictures and videos to others without sending that file to them.
Messaging
Instant Messaging
Instant message anyone on Skype, for FREE.
Send Files
Send documents, photos or presentations of any size for FREE.
SMS Texts
Use Skype to send SMS texts to mobile phones. It’s quick simple and offers even greater
value on sending text messages abroad. SMS rates start at 4 cents a minute.
Facebook
Skype and Facebook have teamed up to make video and voice calls, as well as send instant messages, to all your Facebook friends direct from Skype.
THE END
Full transcript