Skype
From Network Dictionary Wiki
Skype (Template:IPA2, rhymes with type) is a software program created by the Swedish and Danish entrepreneurs Niklas Zennström and Janus Friis. Skype allows users to make telephone calls over the internet to other Skype users free of charge, or to landlines and cell phones for a fee. Additional features include instant messaging, file transfer, short message service, video conferencing and its ability to circumvent firewalls.
The Skype Group, acquired by eBay in September 2005, has headquarters in Luxembourg, with offices in London, Tallinn, Tartu, Prague<ref>Template:Cite web</ref> and San Jose, California. Skype experienced rapid growth in both popular usage and software development since the launch, of both its free and its paid services.
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Features
SkypeOut
SkypeOut allows Skype users to call traditional telephone numbers, including mobile telephones, for a fee. This fee is as low as US$0.021 per minute for most developed countries, and as high as US$2.142 per minute for calls to the dependency of Diego Garcia. Beginning January 2007, Skype also charges an equivalent of €0.039 for each SkypeOut call, in addition to the ordinary rate.<ref>Template:Cite web</ref> After 180 days of not making a SkypeOut call the Skype balance expires. As of January 30, 2007, SkypeOut calls to Canada and the United States are no longer free.
SkypeOut calls to most toll free numbers in France (+33 800, +33 805, +33 809), Poland: (+48 800), UK: (+44 500, +44 800, +44 808) and the United States and Canada: (+1 800, +1 866, +1 888 ) are free for all Skype users, even if they do not have the SkypeOut service.<ref>Free calls to toll-free phone numbers global beta</ref><ref>Template:Cite web</ref> However, for many other countries SkypeOut doesn't support calling toll-free and premium rate numbers, and SkypeOut doesn't support calling emergency numbers (such as 112 the Universal Emergency number for GSM mobile phones, 911 in Canada and the USA, 000 in Australia and 999 In the UK).
SkypeIn
SkypeIn allows Skype users to receive calls on their computers dialed by regular phone subscribers to a local Skype phone number. It permits users to subscribe to numbers in Australia, Brazil, Chile,<ref name="skypeincountries">Template:Cite web</ref> Denmark, the Dominican Republic, Estonia, Finland, France, Germany, Hong Kong, Ireland, Japan, Mexico, New Zealand,<ref name="skypeincountries" /> Poland, Romania, Sweden, Switzerland, UK, and the United States.
For example, a user in San Francisco could create a local telephone number in Helsinki. Callers from Helsinki would pay only local rates to call that number. Some jurisdictions such as France and Norway, however, forbid the registration of their local telephone numbers to anyone without a physical presence or citizenship in the country.
Videoconferencing
First introduced in January 2006, Skype provides videoconferencing for Windows, Mac OS X and Linux (Skype 2.0 or above required). With version 3.6.0.216 for Windows, Skype now supports “High Quality Video" with quality and features (e.g. full-screen and screen-in-screen modes) similar to those found in middle-range video-conferencing systems.<ref> Skype User Guide Template:Cite web </ref>
Major events
- 2002
- September 2002: investment from Draper Investment Company.
- 2003
- April 2003: Skype.com and Skype.net domain names registered.
- August 2003: First public beta version released.
- 2005
- September 2005: SkypeOut banned in South China.<ref>Template:Cite web</ref>
- October 2005: eBay purchased Skype (Oct 14).<ref>Template:Cite web</ref>
- December 2005: videotelephony introduced.<ref>Template:Cite web</ref>
- 2006
- April 2006: Number of registered users reaches 100 million.
- October 2006: Skype 2.0 for Mac is released, the first full release of Skype with video for Macintosh.
- December 2006: Skype announces a new pricing structure as of January 18, 2007, with connection fees for all SkypeOut calls.<ref>Skype to Announce Disruptive Pricing Strategy for SkypeOut Retrieved: December 19, 2006</ref> Skype 3.0 for Windows is released.<ref>What is Skype?</ref>
- 2007
- March 2007: Skype 3.1 is released, adding some new features, including Skype Find and Skype Prime. Skype also released a 3.2 beta with a new feature called Send Money which allows users to send money via PayPal from one Skype user to another.
- August 2007: Skype 3.5 for Windows released with additions such as video in mood, inclusion of video content in chat, call transfer to another person or a group, auto-redial.
- August 15, 2007: Skype 2.7.0.49 (beta) for Mac OS X released adding availability of contacts in the Mac Address Book to the Skype contact list, auto redial, contact groups, public chat creation, and an in-window volume slider to the call window.
- August 16 / August 17, 2007: Skype users unable to connect to full Skype network in many countries.<ref>http://www.chron.com/disp/story.mpl/ap/fn/5059323.html</ref><ref>Template:Cite web</ref> Skype reports the system-wide crash was the result of exceptional number of logins after a Windows patch reboot ("Patch Tuesday").<ref>Template:Cite news</ref>
- November 2007: Skype users are set to lose their 020 7 numbers after 20 December 2007.<ref>Template:Cite news</ref>
- 2008
- January 30 2008: Skype Released for the Sony PSP handheld gaming system.
Usage and traffic
| Date | Total user accounts (in millions) | Skype to Skype minutes (in billions) | Skype Out minutes (in billions) | Net revenue USD (in millions) |
|---|---|---|---|---|
| Q1 2006 | 95 | 6.9 | 0.7 | 35 |
| Q2 2006 | 113.1 | 7.1 | 0.8 | 44 |
| Q3 2006 | 135.9 | 6.6 | 1.1 | 50 |
| Q4 2006 | 171.2 | 7.6 | 1.5 | 66 |
| Q1 2007 | 195.5 | 7.7 | 1.3 | 79 |
| Q2 2007 | 219.6 | 7.1 | 1.3 | 90 |
| Q3 2007 | 245.7 | 6.1 | 1.4 | 98 |
As of September 30, 2007, Skype had a cumulative number of unique user accounts of 246 million. Users may register more than once, and as a result, may have more than one account.
It was reported that 10,140,836 concurrent Skype users were online as of October 30, 2007.<ref>Template:Cite web</ref>
| Date | Users <ref>Template:Cite web</ref> | Days |
|---|---|---|
| 2008-01-07 | 11,000,000 | 84 |
| 2007-10-15 | 10,000,000 | 259 |
| 2007-01-29 | 9,000,000 | 82 |
| 2006-11-08 | 8,000,000 | 71 |
| 2006-08-29 | 7,000,000 | 155 |
| 2006-03-27 | 6,000,000 | 66 |
| 2006-01-20 | 5,000,000 | 92 |
| 2005-10-20 | 4,000,000 | 155 |
| 2005-05-18 | 3,000,000 | 93 |
| 2005-02-14 | 2,000,000 | 117 |
| 2004-10-20 | 1,000,000 | 418 |
| 2003-08-29 | 0 | - |
Although the volume of international traffic routed via Skype is significant, the quantity is small when compared to the cumulated global switched and VoIP traffic. Computer-to-computer traffic between Skype users in 2005 was equivalent to 2.9% of international carrier traffic in 2005 and approximately 4.4% of total international traffic base of 264 billion minutes in 2006.<ref>Template:Cite web</ref>
Skype incorporates some features which obfuscate its traffic, but it is not specifically designed to thwart traffic analysis and therefore does not provide anonymous communication. Some researchers have also been able to watermark the traffic so that it is identifiable even after passing it through an anonymizing network [1].
System and software
Operating systems
Versions now exist for Microsoft Windows (2000, XP, Vista and Windows Mobile), Mac OS X (Intel and PPC) and Linux (32-bit x86 only). Under Windows, Skype can also be run from a USB stick without requiring to be installed on the target computer.<ref> Skype VoIP User Guide, FAQ, Hints and Resources Template:Cite web</ref> The Linux version runs on FreeBSD through its Linux binary compatibility layer. Skype can also run in Solaris branded zones.
The Windows user interface was developed in Pascal using Delphi, the Linux version is written in [[C++]] with Qt, and the Mac OS X version is written in Objective-C with Cocoa.<ref>Template:Cite web</ref>
Detailed changelogs
Skype on mobile devices
Skype offers its own mobile phone under the brand name Skypephone, which runs a BREW OS. Skype is also available on mobile devices running Windows Mobile <ref>Skype on your mobile device</ref> The official Symbian version is currently under development<ref> Skype for Symbian Coming</ref>. Skype is also available on Symbian and Java as part of X-Series. Moreover, thanks to a third party developer, it is also possible to run Skype in a Symbian environment using Fring, which also offers other services. It has just been released on the PSP slim firmware 3.90 in late January, 2008.
Skype protocol
Skype uses a proprietary Internet telephony (VoIP) network. The protocol has not been made publicly available by Skype and official applications using the protocol are closed-source. The main difference between Skype and VoIP clients is that Skype operates on a peer-to-peer model, rather than the more traditional server-client model. The Skype user directory is entirely decentralized and distributed among the nodes in the network, which means the network can scale very easily to large sizes (currently about 240 million users)<ref>1 million Joost users prepare for year-end launch</ref> without a complex and costly centralized infrastructure.
Resource usage
Skype accesses the hard disk several times each minute. This can be verified by observing the HDD's activity LED, or by using a file access monitor such as FileMon.<ref>Template:Cite web</ref> With regard to internet bandwidth, certain users are selected by software to act as "supernodes"<ref> Skype FAQ Template:Cite web </ref>. Under certain conditions, Skype is reportedly willing to accept thousands of connections, but is stated to limit itself to 40 kb/s upload and download.<ref>Template:Cite web</ref><ref>Template:Cite web</ref><ref>Template:Cite web</ref>
Security
Secure communication is a feature of Skype. The encryption cannot be turned on or off. The user is not involved in the encryption process and therefore does not have to deal with the issues of public key infrastructure. Skype reportedly uses non-proprietary, widely trusted encryption techniques: RSA for key negotiation and the Advanced Encryption Standard to encrypt conversations.<ref>Template:Cite web</ref>
Skype provides an uncontrolled registration system for users: registration requires no proof of identity. Although this permits users to use the system safely without revealing real-life identities to other users of the system, the lack of authentication means there is no guarantee that those communicated with are who they say they are in real life. The downside of this is that it is easy to use the personal name (but not identity) of a trusted person as a Skype nickname and trick a naive user into revealing information or executing a program sent to them.
Supported audio codecs
Criticisms
Template:Criticism-section Due to the design of the protocol, if given access to an unrestricted network connection, Skype clients can become supernodes. These supernodes hold together the peer-to-peer network and provide data routing for other clients behind more restrictive firewalls, which can generate a significant amount of bandwidth usage. For this reason, some network providers, such as universities, have banned the use of Skype.<ref>Template:Cite web</ref> The French ministry of research strongly discourages the use of Skype in all French public universities and laboratories, especially those with sensitive research, leading to an outright ban in many laboratories.<ref>Alert for the defense security officer of CNRS</ref>
A third party paper analyzing the security and methodology of Skype was presented at Black Hat Europe 2006.<ref>Template:Cite web</ref> It analyzed Skype and made these observations:
- Heavy use of anti debugging techniques (used to deter development of alternative clients, hacking tools)
- Significant use of obfuscated code (slows reverse engineering, less description of what program code does internal to the executable file)
- Keeps chatting on the network, even when idle (even for non-supernodes. May be used for NAT traversal)
- Blind trust in anything else speaking Skype
- Ability to build a parallel Skype network
- Lack of privacy (Skype has the keys to decrypt calls or sessions)
- Heap overflow in Skype
- Skype makes it hard to enforce a (corporate) security policy
- "No way to know if there is/will be a backdoor"
SkypeOut rates are "per minute" based, contrary to the trend in charges for calls from conventional telephones Template:Fact. In some countries, many calls are charged at a specified fixed amount per call. In this method, SkypeOut is more expensive for longer calls, whereas it is cheaper for relatively short calls.
There have been complaints about Skype's poor customer support.<ref>Template:Cite web</ref> As of June 2007, Skype still does not provide a direct way of contacting its customer support, relying solely on its web portal for all related issues. There have also been criticisms of Skype blocking and disabling customer accounts from using the SkypeOut service.<ref> SKYPE Account Blocked - Skype Forums</ref>
When Skype 2.0 was released, AMD filed a lawsuit claiming the software offers 10-way conference calls on dual core Intel processors, while other chips, including all AMD chips, will only offer 5-way conference calls.<ref>Template:Cite web</ref>
While available for Windows, Mac OS X and Linux (i386 platform) operating systems, there is no Skype version for the Palm OS, used in mobile devices like the Treo 700p smartphone nor for the Linux versions for different architectures.
Skype has been criticized in the Linux community for bugs and delays in the Linux version.<ref>Template:Cite web</ref>
The Mac OS X version lacks some of the advanced features included in Skype for Windows.Template:Fact
Users of Skype on Mac OS X report poor audio quality when connecting to Mac/Mobile clients, with newer audio engines showing more and more problems. Audio quality when connecting from Mac to Windows seem to be acceptable.
Skype was also found to access BIOS data<ref>pagetable.com » Blog Archive » Skype Reads Your BIOS and Motherboard Serial Number</ref> to identify individual computers and provide DRM protection for plug-ins.<ref>Skype Security Blog - Skype Extras plug-in manager</ref><ref>The Register » Skype snoop agent reads mobo serial numbers</ref>
It can not be assured that Skype calls are not interceptable. Skype provides end to end encryption for connections between users however in an interview at cnet.com Skype chief security officer Kurt Sauer would not eliminate this possibility.<ref>Interview at CNet</ref>
Skype cannot be used with VOIP analogue telephone adapters (ATAs), which use SIP, H323, and other protocols. Consequently, Skype users are limited to either using software phones or expensive Skype only hardware. However, there are applications that enable Skype users to connect to SIP providers <ref>Uplink Skype to SIP Adapter Software - Connect SIP to the Skype Network</ref>.
SkypeOut has been criticized because it does not support caller ID in the United States, where people frequently reject calls from unrecognized numbers.<ref> (SDS-208) Skype losing SkypeOut Customers due to lack of caller id in the US. Skype Developer Zone.</ref> The recipient sees "0123456789" instead of a real phone number. By contrast, the Gizmo service shows the user's call-in number on caller ID.<ref> Does my Caller-ID show when I call a regular phone? Gizmo Project FAQ.</ref>
Skype Limited (corporate)
On October 14, 2005, eBay acquired the company for €1.9 billion in cash and stock, plus an additional €1.5 billion in rewards (earn out) if goals are met by 2008.<ref>Template:Cite web</ref><ref>Template:Cite news</ref>
Skype Limited faces challenges from two main directions. Firstly it faces legal challenges to its intellectual property and secondly it faces political pressures by governments wishing to control the telecommunications systems of their respective countries.
United States, CALEA 2006
In May 2006, the FCC successfully applied the Communications Assistance for Law Enforcement Act to allow wiretapping on digital phone networks. Skype is not yet compliant to the Act, and has so far stated that it does not plan to comply.<ref>Can Skype Keep Its Secrets?</ref>
IDT lawsuit
On June 1, 2006, Net2Phone (the Internet telephone unit of IDT Corp.) filed a lawsuit against eBay and Skype accusing the unit of infringing Template:US patent, which was granted in 2000.<ref>Template:Cite news</ref>
China 2005
Skype is one of many companies (others include AOL, Google, Microsoft, Yahoo, Cisco) which have cooperated with the Chinese government in implementing a system of Internet censorship in the People's Republic of China. Niklas Zennström, chief executive to Skype, told reporters that its joint venture partner in China is operating in compliance with domestic law. "TOM Online had implemented a text filter, which is what everyone else in that market is doing," said Zennström. "Those are the regulations," he said. "I may like or not like the laws and regulations to operate businesses in the UK or Germany or the US, but if I do business there I choose to comply with those laws and regulations. I can try to lobby to change them, but I need to comply with them. China in that way is not different."<ref>Template:Cite news</ref>
Since late September, users in China trying to download the Skype software are redirected to the TOM site from which a modified Chinese version can be downloaded. Activists in China are warning about the possibility that TOM's versions have or will have more trojan capability.<ref>Dynamic Internet Technology Inc. Alleges Skype Redirects Users in China to Censorware Version - Ten Days After Users Are Able To Download Freegate Software Through Skype, TMCnet, September 24, 2007</ref>
See also
- Skype Protocol
- Presence information
- Voice over IP
- Instant messaging
- Mobile VoIP
- IP Phone
- Videoconferencing
- Secure communication
Alternatives
- Voipfone
- Gizmo Project
- SightSpeed
- WengoPhone
- VoipBuster
- VZOchat
- OoVoo
- SIP-based services
- AOL Instant Messenger/AIM Call Out
- Yahoo! Messenger/Yahoo! Voice
References
External links
- Official Skype website
- Scientific Research on Skype (Reverse Engineering, etc.)
- White paper on Skype, focus on supernodes
- Skype Security Evaluation by Tom Berson (Anagram Laboratories)
- VoIP and Skype security by Simson L. Garfinkel (Tactical Technology Collective)
- Skype security, obfuscation and protection against reverse-engineering techniques analyzed at Black Hat conference 2006
Skype Phones
- MyToGo for Skype Converts your other phones/devices to a Skype Phone
- Simplyphone Skype hardware partner developing Skype Certified plug-in and wireless phones
- RTX Skype partner developing USB and embedded cordless Skype phones
- Belkin Wi-Fi Phone for Skype
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