Skype (IPA pronunciation: /skaɪp/, rhymes
with type) is a software program created by the entrepreneurs Niklas Zennström and Janus Friis. Skype allows users to make telephone calls from their
computer 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 [1] and
San Jose, California. Skype has experienced rapid growth in both popular usage and
software development since launch, both of its free and its paid services.
Features
-
SkypeOut
SkypeOut rates as of May 2006, in USD$ per minute
SkypeOut allows Skype users to call traditional telephone numbers, including mobile telephones, for a fee. This fee is
as low as US$0.024 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.[2] 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, +1 877, +1 888 ) are free for all Skype users, even if they do not
have the SkypeOut service. [2][3] . 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 in Europe or 911 in the U.S.A.).
Quality of service is not guaranteed. Dropouts, broken connections and compression distortion are frequently observed by
users.
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[3] , Denmark, the
Dominican Republic, Estonia, Finland, France, Germany, Hong Kong, Ireland, Japan, Mexico, New Zealand,[3] Poland, Romania,
South Korea, 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, however, forbid the registration of their local telephone numbers
to anyone without a physical presence or citizenship in the country.
Major events
- 2002-2005
|
- 2006-2007
- April 2006: 100 million registered users.
- 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.[7] Skype 3.0 for
Windows is released.[8]
- 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. [9]
- 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.[10][11] Skype
reports the system-wide crash was the result of exceptional number of logins after a Windows patch reboot ("Patch Tuesday").[12]
|
Usage and traffic
A typical early version of Skype 1.0, running on a
Windows XP desktop
| 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 |
N/A |
N/A |
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 ten million concurrent Skype users were online as of October 15
2007.[13]
| Date |
[14] Users online |
Days |
| 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 still 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.[15]
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
[4].
System and Software
Skype 1.4, running on a
Linux desktop, over 7,630,000 people online
Operating systems
Versions now exist for Microsoft Windows (2000, XP and Windows Mobile),
Mac OS X and GNU/Linux. Under Windows, Skype can also be run
from a USB stick without requiring to be installed on the target computer[16]. Although Skype's web site does not state compatibility with Windows Vista, there appear to be no problem reports from running Skype on Vista. The Linux version runs
on FreeBSD through its Linux binary compatibility layer; the Fedora Core version works fine, provided the user switches on the microphone in the
GNOME sound settings. The official Symbian version is
currently under development.[17] but it's already
possible to run Skype in a Symbian environment using Fring[18].
Detailed changelogs
-
Skype protocol
-
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)[19] 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.[20] With regard to internet bandwidth, certain users are selected by software to act as "supernodes". 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.[21][22][23]
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.[24]
Skype provides an uncontrolled registration system for users: registration requires no proof (by means of state-issued
ID card) of the identity of the user. This works two ways: you can use the system
safely without revealing your real-life identity to other users of the system, but on the other hand you have no guarantees that
the person you communicate with is the one 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[25]
Criticisms
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.[26]
A third party paper analyzing the security and methodology of Skype was presented at Black Hat Europe 2006.[27] 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. 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 [28]. 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. [29]
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.[30]
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
PowerPC version of Linux.
Skype has been criticized in the Linux community for bugs and delays in the Linux version
[5]. The
Mac OS X version also lacks some of the advanced features included in Skype for
Windows.[citation needed]
Skype was also found to access BIOS data[31] to
identify individual computers and provide DRM protection for plug-ins.[32][33]
Skype 1.4.0.99 has also been found to read the /etc/passwd and Firefox profile on Linux machines[34].
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 [35].
Skype can not be used with real VOIP ATA devices and instead requires expensive Skype only hardware or limits you to using
software phones.
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.[36][37]
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.[38]
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 U.S. Patent , which was granted in 2000.[39]
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."[40]
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.[41]
See also
Alternatives
References
- ^ Jaanus Kase. Skype is
expanding engineering to Prague. Skype Blogs. Retrieved on 2006-12-05.
- ^ Connection Fee for SkypeOut Calls. skype.com. Retrieved on 2007-01-19.
- ^ a b Villu Arak. Four new SkypeIn
countries. Skype Blogs. Retrieved on 2007-08-13.
- ^ Jack McCarthy. China bans Skype.
InfoWorld. Retrieved on 2006-06-17.
- ^ eBay Completes
Acquisition of Skype. eBay. Retrieved on 2006-06-17.
- ^ Skype Launches Next
Generation Free Internet and Video Calling for Everyone. Skype. Retrieved on 2006-06-17.
- ^ Skype to Announce
Disruptive Pricing Strategy for SkypeOut Retrieved: December 19, 2006
- ^ What is Skype?
- ^ "Skype Takes
Video One Step Further".
- ^ http://www.chron.com/disp/story.mpl/ap/fn/5059323.html
- ^ Error in
Skype’s Software Shuts Down Phone Service. NY Times. Retrieved on 2007-08-17.
- ^ "Skype blames
outage on user reboot".
- ^ Ten million online.
- ^ 8 million onliners. skypenumerology. Retrieved on 2006-11-08.
- ^ International
carriers' traffic grows despite Skype popularity. TeleGeography Report and Database. Retrieved on 2006-12-07.
- ^ Skype VoIP User Guide, FAQ, Hints and Resources How to run Skype from a USB stick.
- ^ Skype for
Symbian Coming
- ^ Fring
official website
- ^ 1 million
Joost users prepare for year-end launch
- ^ FileMon for Windows. Sysinternals. Retrieved on 2006-06-17.
- ^ Bruno Giussani. Swiss magazine digs deeper in social
blog. Lunch over IP. Retrieved on 2006-06-17.
- ^ Fear of a Skype Planet. Paul Kedrosky. Retrieved on 2006-06-17.
- ^ Skype
supernodes sap bandwidth. Computerworld. IDG. Retrieved on 2006-06-17.
- ^ Skype Privacy FAQ. Skype. Retrieved on 2006-12-05.
- ^ Is
Skype's own codec good? - Skype Forums. Retrieved on 2007-08-20.
- ^ Ryan Paul. More universities banning
Skype. Ars Technica. Retrieved on 2007-01-12.
- ^ Philippe BIONDI and Fabrice DESCLAUX. Silver Needle in the Skype. blackhat. Retrieved on 2006-03-02.
- ^ Ben Charny. Skype callers: 'Customer service, please?'.
- ^ [1]
- ^ Tom Krazit. AMD's lawyers call on Skype.
- ^ pagetable.com » Blog Archive » Skype Reads Your BIOS and Motherboard Serial
Number
- ^ Skype Security Blog - Skype
Extras plug-in manager
- ^ The Register » Skype snoop agent reads mobo
serial numbers
- ^ Skype Forums » English » Platforms, community support »
Skype for Linux » Skype
1.4.0.99 reads /etc/ passwd and firefox profile!
- ^ Interview at CNet
- ^ eBay Completes
Acquisition of Skype. Skype. Retrieved on 2006-06-12.
- ^ "eBay to buy Skype in $2.6bn deal", BBC, September 12, 2005.
- ^ Can Skype Keep Its
Secrets?
- ^ Pallavi Gogoi. "Skype Under
Attack", Business Week, McGraw Hill, June 6, 2006.
- ^ "Skype says texts are
censored by China", FT.com, Financial Times, April 18, 2006.
- ^ 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
External links
Skype Phones
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