What is Skype?
Skype is a little piece of software that lets you make free calls to anyone else on
Skype, anywhere in the world. And even though the calls are free, they are really
excellent quality. If you and your friends, family or business contacts are using webcams,
you can also make free video calls. You can even call landlines and mobile phones at
really cheap per minute rates (and there’s no setup or subscription fee).
Dow nload now
Skype is free to download and easy to use.
Do more than just calling
Just like instant messengers, you can also use Skype to chat and
not just with one other person at a time, but with up to 100 people in a group chat. If it’s a
really nice group chat, you can bookmark it and find it later, which is handy for persistent
chats with family or business contacts.
Find people to talk to
Simply find and add contacts to your contact list, and when you have people on
your list, you can see if they’re online, offline, busy or not sitting at their computer right
Importing contacts lets you find people among your contacts who are already on
Skype. Even if they’re not using Skype yet, you can still call your Microsoft Outlook®
contacts directly from Skype.
Shared Groups is handy when your contact list is full of friends and family. You
can then easily organise them by creating and managing groups of contacts. And with
Shared Groups, all your friends or your latest project group can stay in touch and be
automatically updated when a new person joins the group.
It just works. No worries
Skype works on most kinds of computers — Windows, Mac OS X,
Linux and Pocket PCs. Calls, chats and file transfers work between all kinds of
Skype automatically encrypts calls, chats and file transfers before sending it
through the internet so no-one can intercept your call, text or file transfer. And it’s
completely free of advertising, so you won’t be disturbed by annoying pop-ups or
Useful things that cost a little
You can talk to anyone on Skype over the Internet for free, and you’ll always be able to
do that. There are some other useful things you can do on Skype that aren’t free (but
they’re pretty cheap, actually). Learn more about what is free, and what is not.
SkypeOut is a cheap way to call from Skype to landlines and mobile phones. You can
also use SkypeOut to forward calls to your Skype to your home number or mobile phone.
SkypeIn is a number your friends can call from any phone and you pick up the call in
Skype. You can get numbers in one or more of the places offered, and receive calls in
Skype from anywhere in the world.
Skype Voicemail takes your calls when you’re busy or offline.
Skype SMS lets you send SMS messages to your friends’ mobile phones from Skype.
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Skype on Windows XP
Maintainer: Skype Technologies S.A.
Stable 18.104.22.168 (Windows),
release: 22.214.171.124 (Linux),
126.96.36.199 (Mac OS X),
188.8.131.52 (Pocket PC)
(December 13, 2006) [+/-]
N/A (N/A) [+/-]
Use: P2P/VoIP/instant messaging/
Skype (IPA pronunciation: /skʌɪp/, rhymes with type) is a proprietary peer-to-peer Voice
over IP (VoIP) network founded by the entrepreneurs Niklas Zennström and Janus Friis,
also founders of the file sharing application Kazaa. It competes against existing open
VoIP protocols such as SIP, IAX, and H.323. The Skype Group, acquired by eBay in
October 2005, is headquartered in Luxembourg, with offices in London, Tallinn and
Skype has experienced rapid growth in both popular usage and software development
since launch, both of its free and its paid services. The Skype communications system is
notable for its broad range of features, including free voice and video conferencing, and
its ability to use peer to peer (decentralized) technology to overcome common firewall
and NAT (Network address translation) problems.
1 System and software
o 1.1 Technology
o 1.2 Security
1.2.2 Resource usage
1.2.3 Confidentiality of data
1.2.4 Integrity/authenticity of data
1.2.5 Authenticity of user identity
1.2.6 Traffic analysis
o 1.3 Milestones and releases
o 1.4 Usage
o 1.5 Traffic volume
o 2.1 SkypeOut
o 2.2 SkypeIn
o 2.3 Skype voicemail
o 2.4 Skype chat
o 2.5 Skype video calling
o 2.6 Skypecasts
o 2.7 Skype SMS
o 2.8 Skype web toolbar
o 2.9 Skype Zones
o 2.10 Skype history logs
o 2.11 Skype Hardware
o 2.12 Additional Tools
4 Legal and political aspects
o 4.1 Legal challenges
4.1.1 Streamcast lawsuit
4.1.2 IDT lawsuit
o 4.2 Political issues
4.2.1 China 2005
4.2.2 France 2006
4.2.3 India 2006
5 Skype group (corporate)
6 Competition and alternatives
o 6.1 Open source alternatives
o 6.2 Closed source alternatives
7 See also
9 External links
 System and software
The caller ID information is masked when a SkypeOut call is placed.
A typical early version of Skype 1.0, running on a Windows XP desktop
Skype users essentially make telephone calls and video calls through their computer
using Skype software and the internet. The basis of the system is free communication
between users of Skype software; however the product also allows Skype users to
communicate with users of regular landline and mobile telephones. This software is
currently available free of charge and can be downloaded from the company website, but
the software is proprietary and the Skype protocol is unpublished.
The main difference between Skype and other 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 decentralised and distributed among the nodes in the network, which
means the network can scale very easily to large sizes (currently just over 100 million
users) without a complex and costly centralised infrastructure.
Skype also routes calls through other Skype peers on the network to ease the traversal of
Symmetric NATs and firewalls. This, however, puts an extra burden on those who
connect to the Internet without NAT, as their computers and network bandwidth may be
used to route the calls of other users.
The selection of intermediary computers is fully automatic, with individual users having
no option to disable such use of their resources.
This fact is not clearly communicated however and seems to contradict the license
agreement, which limits Skype's usage of the user's "processor and bandwidth [to the]
purpose of facilitating the communication between [the user] and other Skype Software
users" (section 4.1).
The Skype code is closed source, and the protocol is not standardized but proprietary; this
has raised suspicion and drawn some criticism from software developers and users.[citation
The Skype client's application programming interface (API) opens the network to
software developers. The Skype API allows other programs to use the Skype network to
get "white pages" information and manage calls.
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. Parts of the client use Internet Direct (Indy), an open source socket
Skype generates a significant amount of discussion on how secure its traffic really is. It
has had an impact upon the security and culture of VoIP telephony because of this
discussion and several design principles:
All Skype traffic is encrypted by default and the user cannot turn it off.
Skype reportedly uses openly available, strong encryption algorithms.
The user is not involved in the encryption process and therefore does not have to
deal with the issues of Public key infrastructure.
This has had an effect upon the rest of the market as they seek to offer competitive
products. The security of internet communication has become an issue of which people
are more aware and secure communication a feature they want to see in the products they
Since the Skype code is proprietary and closed source, the security of the software cannot
be firmly established by independent experts; thus, its users—experts and non-experts
alike—may base their usage of the product on merely trusting the manufacturer and
behavior of the software downloaded from sources authorized by the manufacturer. In
2004, Niklas Zennstrom, co-founder of Skype, appeared to admit in an article on The
Register that the current security model used a relatively short key size, relied upon
security through obscurity, and would not withstand open-source scrutiny:
Would he make Skype open-source?
No, that would make its strong 1024 bit encryption and security vulnerable: "We could
do it but only if we re-engineered the way it works and we don't have the time right now."
—Niklas Zennstrom, co-founder of Skype, on the Skype security model
The canonical Skype architecture and security model are described in detail in a book
entitled, Skype: The Definitive Guide from Que Publishing. In addition, at least two
analyses of the Skype code have been published. Tom Berson of Anagram Laboratories,
an encryption and security specialist of over thirty years standing, was invited by Skype
to analyse their source code in October 2005. Separately, a reverse-engineered study by
Philippe Biondi and Fabrice Desclaux, of the actual Skype release package in action, was
presented at BlackHat Europe in March 2006.
The conclusions of the two analyzes were as follows:
There are two sets of issues—discussion of the Skype system in general, and
review of the security within its various parts and communications.
Skype is a "complete black box"—that is, it is extremely hard for the lay user to
identify what it is doing, or what it might be doing, or how appropriately it is
doing it. It uses security through obscurity to make itself troublesome to analyse
or reverse engineer without a significant amount of work, or use of emulation.
Searches for contacts, and connection via supernodes, are trusted instead of
requiring authentication: There are notable "holes" in security in the area of the
global Skype network—in some areas, "Skype trusts any computer that speaks
The Skype software itself uses a great deal of code obfuscation and decryption in
memory, including hundreds of checksummers and other anti-reverse-engineering
The company claims that the protocol includes 1536- and 2048-bit public/private
key pairs. These are not considered excessively long by modern standards, but are
a strong barrier to decryption. Apparently, users of paid services obtain a
replacement 2048 bit key (the 1536 bit key being standard). It also uses 256-bit
AES over 128-bit blocks, which is considered strong.
The Skype system automatically selects certain users with fast CPUs, good
broadband connections and no firewall issues to be either "supernodes" or
"relays", through which other users may connect. Skype can therefore utilise other
users' bandwidth. (Although this is allowed for in the EULA, there is no way to
tell how much bandwidth is being used in this manner). There are some 20,000
supernodes out of many millions of users logged on. Skype Guide for network
administrators  claims that supernodes carry only control traffic up to 5
kbytes/s and relays may carry other user data traffic up to 10 kbytes/s (for one
video call). A relay should not normally handle more than one "relayed
Every package virtually, including the actual software itself, is encrypted, often
by means of public/private key signing methods or AES.
Skype's file-transfer function does not contain any programmatic interfaces to
antivirus products, although Skype claims to have tested its product against
antivirus "Shield" products. If the EICAR test file is sent over Skype's file-
transfer service, every major antivirus product appears to catch the virus and halt
its transmission or reception via Skype.
The lack of clarity as to content means that firewalls and systems administrators
cannot be sure what Skype is doing. (The combination of an invited and a reverse-
engineered study taken together suggest Skype is not doing anything hostile.)
Firewall rules for Ip tables were given to block Skype for corporates.
The full functionality of Skype was not reviewed; both studies appear to have
focused upon its security. Thus, it cannot be said what else may or may not be
The actual communication of any given Skype conversation is reported to appear
relatively secure; both cryptographic analyses concluded that Skype had made
good use of modern encryption techniques and had coded the actual encryption
algorithms correctly within the software.
 Resource usage
A typical early version of Skype 3.0 Beta, running on a Windows XP desktop
Skype accesses the hard disk several times per minute. This can be verified by observing
the HDD's activity LED, or by using a file access monitor such as FileMon. Although
those accesses are small, extremely fast, and safe in the short term, they can be harmful in
the long term. In particular, the continuous access pattern does not allow the disk to enter
"sleep" or "idle" modes while Skype is active, even when offline. This will cause the
computer to consume more energy than otherwise, even when idle, but will not affect the
lifespan of the HD (a hard disk will actually last longer if left spun up compared to being
constantly spun up and down. Spinning down a hard disk is strictly a power-saving
feature). Stronger HDD caching does not seem to improve this behavior.
Also, as mentioned above, 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 40Kb/s upload and download.
 Confidentiality of data
Since a Skype connection may be routed through an intermediate peer, 256-bit AES
encryption actively encodes the data stream of each call, or file transfer. Skype uses
1024-bit RSA keys to secure the pairwise negotiation of an AES symmetric session key
over an untrusted channel (cf. http://www.skype.com/help/faq/privacy.html). Skype
claims that the proprietary session establishment protocol is efficient and prevents both
man-in-the-middle and replay attacks. The software is not self-certifying which means it
needs to connect and login to a centralized Skype server to certify each user's public key.
One possible interception scenario would be for Skype to route a connection via a
specific intermediate peer, which may also be provided with copies of the keys. This
would enable law enforcement authorities to intercept calls with the cooperation of the
Skype company. This Skype-sanctioned man-in-the-middle technique would be
impossible for an end-user to detect.
Skype currently permits multiple concurrent logins: if an attacker is able to obtain a user's
login password, the attacker could login as that user, and change their status to "Hidden".
Thereafter, any chat sessions involving the real user are copied to the hacker's "ghost"
account. If a user keeps their password secure, this is not of concern.
 Integrity/authenticity of data
The integrity of the data, i.e. data modified while traveling though peers, even if
encrypted, is unknown and undocumented. The mechanism and implementation has been
examined in Berson's report (referenced below).
 Authenticity of user identity
Skype provides an uncontrolled registration system for users: registration requires no
proof (in 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
It should be noted that this behavior is common to all digitally provided services: the
exception is certificates from trusted certificate authorities with all the known drawbacks.
 Traffic analysis
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 . Even short
skypeout calls have been traced, leading to the apprehension of at least one suspect.
 Milestones and releases
For detailed changelog see Skype changelog.
September 2002: Skyper Limited January 2006: Skype 2.0 released.
received its founding investment Five million concurrent Skype users
from Draper Investment Company on line.
April 2003: Skype.com and March 2006: A third party paper
Skype.net domain names registered analyzing the security and
August 2003: First public beta methodology of Skype is presented
version released at Black Hat Europe 2006.
June 2004: Beta release of version
0.98.0.28 with first support for April 2006: 100 million registered
SkypeOut. Credits by voucher only users.
initially, then from website. May 2006: Skype 2.5 beta introduces
July 2004: Release of Version 1.0 for Skypecast preview and SMS
Windows. messaging. Skype users spoke for
October 2004: 1 million Skype users 6.9 billion minutes during the first
online simultaneously. quarter 2006. Skype now handles 7%
of the world's long-distance
2005 minutes. Skype for Mac 184.108.40.206
is released, the first Universal build
January 2005: First stable version for of Skype. First major "free minutes"
Mac OS X. offer with SkypeOut to US and
February 2005: 2 million users Canadian landlines and mobile
online simultaneously. phones free until December 2006.
March 2005: SkypeIn Public Beta June 2006 Skype 2.5 for Windows
starts. Skype reports 1 million released. A Mac version with video,
SkypeOut users and 29 million named Skype for Mac 1.5 Beta, is
registered users. 84 million software leaked on the Skype site before
downloads and 5.98 billion talk pulled shortly afterwards.
minutes served. Central contact lists July 2006 Three new Skype toolbars
introduced with v1.2 for Web, email, and desktop
April 2005: Downloaded more than applications, designed to let people
100 million times. initiate voice and video calls, and
May 2005: 3 million online at once. instant messages directly from
computer applications such as
June 2005: Ten billion minutes of Microsoft Outlook and Internet
voice conversation served. Explorer. Skype for Mac 1.5 beta
August 2005: Call forwarding is released officially and a preview
introduced with 1.4 beta. version with Video is also released
September 2005: SkypeOut banned for Mac.
in South China. eBay announces August 2006 Skype for Windows 2.6
purchase of Skype (Sept 12). early preview is released. Seven
October 2005: eBay completes million concurrent users online.
purchase of Skype (Oct 14). 
December 2005: videotelephony September 2006 Skype launches free
introduced in Skype-to-Skype calls SkypeOut calls from France to
with v2.0 beta. landlines in France.
October 2006 Skype 2.0 for Mac is
released, the first full release of
Skype with video for Macintosh.
November 2006 Eight million
concurrent user online. Skype 3.0
beta for Windows is released.
December 2006 Skype 3.0 for
Windows is released.
Versions now exist for Microsoft Windows (2000, XP and CE (Pocket PC)), Mac OS X
and GNU/Linux. The Linux version runs on FreeBSD through its Linux binary
It was reported that eight million concurrent Skype users were online as of November 8,
Date Users online Days
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 -
SR Consulting reviewed 4 million Skype user profiles in October 2005 and produced
some demographic information reported by Skype News and Skype Journal.
Average claimed age: 29.7 years old.
About 46% of Skypers are in Europe, but Brazil and China have the most Skype
users of any country, with China coming in at 13% of the Skype population.
Gender information is inconclusive so far. More than half of all users declined to
state their sex.
 Traffic volume
Although the volume of international traffic routed via Skype is significant, the quantity
is still small when compared to a global switched and VoIP traffic base of 264 billion
minutes. 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 in 2006.
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 USD$0.024 per minute for most developed
countries, and as high as USD$2.142 per minute for calls to the dependency of Diego
Garcia. After 180 days of not making a SkypeOut call the Skype balance expires. This
policy makes Skypeout a poor service for infrequent users as they will often lose their
entire account balance.
Until December 31 2006, SkypeOut calls originated within the USA and Canada to
destinations within USA and Canada are free. . The standard SkypeOut rate will be
charged starting in 2007, although an unlimited usage plan for North American calls is
SkypeOut calls to toll free numbers in France (+33 800, +33 805, +33 809) , Poland:
(+48 800) , UK: (+44 500, +44 800, +44 808 ) and the USA 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. . SkypeOut calls to toll-free numbers in Belgium (+32 800) do not work.
SkypeIn allows Skype users to receive calls on their computers dialed by regular phone
subscribers to regular phone numbers. Permits users to subscribe to numbers in Australia,
Brazil, Denmark, Estonia, Finland, France, Germany, Hong Kong, Japan, Poland,
Sweden, Switzerland, UK and USA.
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.
 Skype voicemail
Skype Voicemail was released on March 10, 2005. This service allows callers to leave
voice-mail messages for Skype users who are indisposed.
Skype Voicemail has experienced numerous problems over the past year and users
complain that many voice mail calls are never received. Additionally, the SkypeIn service
occasionally fails to record certain incoming calls on the program's history page. These
problems have not been completely resolved.
 Skype chat
A typical early version of Skype 3.0 beta Public Chats, running on a Windows XP
Skype supports group text chat with an interface similar to IRC with 100 People.
The Macintosh version uses the same message view style format as Adium, though with a
different filename extension. Message view styles made for Adium can be installed for
Skype, and they do not even need to be renamed. There are a couple of cosmetic
bugs, but ignoring those, Adium styles work without modification. This feature is not
present in the Windows, Linux, and Pocket PC versions of Skype.
 Skype video calling
On Windows XP (Windows 2000 users require DirectX 9.0 for video calls) and Mac,
Skype 2.0 (and above) supports videoconferencing, making Skype one of the few cross-
platform video conferencing solutions between Windows and Mac. Skype only supports
one-to-one video chat.
Skypecasts was released on May 3, 2006. Skypecasts are live, moderated conversations
allowing groups of up to 100 people to converse, moderated by the �host� who is able
to mute, eject or pass the virtual microphone to participants when they wish to speak.
Skypecasts do not support chat windows to share text information (such as URLs) with
 Skype SMS
One of features of Skype 2.5 (and above) is the ability to send SMS messages to mobile
phone numbers (a feature commonly used in other IM software such as ICQ, AOL Instant
Messenger, Yahoo Messenger and Windows Live Messenger).
 Skype web toolbar
The Skype Web Toolbar recognizes phone numbers and Skype Skype. Currently only
available for Internet Explorer and Mozilla Firefox on Windows. There is also a toolbar
 Skype Zones
Skype Zones Beta is software powered by Boingo that provides access to Skype through
Skype-friendly hot spots.
 Skype history logs
A log file is created for each contact on a user's contact list. Log files are stored locally,
meaning they are not available if a user switches computers. By default, the option to log
conversations is disabled, but can be enabled in the tools / privacy panel.
 Skype Hardware
Recently a number of manufactures have launched hardware devices compatible with
Skype. These are usually either tethered to a PC, or have a built-in Wi-Fi client to allow
calling from Wi-Fi hotspots like the Netgear SPH101 Skype Wi-Fi Phone.
 Additional Tools
Skype Beta version 3.0 provides additional tools under "Do More" Submenu. Tools
added include the 'Pamela Voice' recorder for recording voice calls, plus many games.
Skype has been criticised over its use of a proprietary protocol, instead of an open
standard like H.323, IAX, or SIP, since this makes it impossible for other providers to
interact with the Skype network. There are of course clear business reasons for this, since
it helps protect the SkypeOut revenue stream from competition.
A design limitation of Skype is that, if given access to an unrestricted network
connection, Skype clients can become supernodes. These supernodes hold together the
peer-peer network and provide data routing for those behind restrictive firewalls.
Unfortunately, these supernodes can generate a significant amount of bandwidth. For this
reason some network providers, such as universities, have banned Skype.
A third party paper analyzing the security and methodology of Skype was presented at
Black Hat Europe 2006. 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 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"
Another criticism of Skype has been content filtering. See: Internet censorship in the
People's Republic of China.
While available for most operating systems, there is no Skype version for the Palm OS
which is widely used in mobile devices like the Treo 700p.
Skype has been heavily criticized in the Linux community for bugs and delays in the
Linux version .
 Legal and political aspects
Skype faces challenges from two main legal and political directions - challenges to its
intellectual property, and political concerns by governments who wish to exert more
formal control over aspects of their telecommunications systems.
Skype's technology is proprietary and closed to outside review. It is unknown to what
extent it can potentially intrude upon other parties' patents and copyrights. It is not
unreasonable, therefore, to expect legal challenges from third parties concerning
Intellectual Property issues.
 Legal challenges
 Streamcast lawsuit
In January, 2006, StreamCast Networks filed a complaint in U.S. District Court in Los
Angeles, accusing Skype of stealing its peer-to-peer technology. The $4.1 billion lawsuit
did not initially name eBay, Skype's parent company; however, the lawsuit was amended
in a filing with Federal Court in the Central District of California on May 22, 2006, to
include eBay and 21 other parties as defendants.
Streamcast seeks a worldwide injunction on the sale and marketing of eBay's Skype
Internet voice communication products, as well as billions of dollars in unspecified
 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 6,108,704 , which was
granted in 2000.
 Political issues
 China 2005
For a brief period, SkypeOut was blocked in some regions of mainland China (notably
Shenzhen) by the operator China Telecom for undisclosed reasons; it has been speculated
that this may relate to SkypeOut's ability to take lucrative international and long-distance
business away from the People's Republic of China's state-controlled telecommunications
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 mainland China. Critics of such policies argue that it is wrong for
companies to assist in such policies, which might allow them to profit from censorship
and restrictions on freedom of the press and freedom of speech. Human rights advocates
such as Human Rights Watch and media groups such as Reporters Without Borders state
that in their view, if companies stopped contributing to the authorities' censorship efforts
the government could be forced to change.
Niklas Zennstrom, 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 Mr Zennstrom.
"Those are the regulations." "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."
 France 2006
In September 2005, the French Ministry of Research, acting on advice from the general
secretariat of national defence, issued an official disapproval of the use of Skype in
public research and higher education; some services are interpreting this decision as an
outright ban. The exact reasons for the decision were not given, but speculatively may
relate to issues noted earlier, relating to inability to monitor the nature of information
being communicated, possible extreme resource usage, or unknown potential actions of
 India 2006
In December 2006, the Indian Government announced they are preparing a crackdown on
VoIP services, citing security risks and loss of revenue. The clampdown is targeted at
outsourcers and other Indian IT businesses that use foreign owned VoIP services, such as
Skype and Yahoo!, to cut their phone bills and evade the six percent revenue share and
12 percent tax imposed on local services by the government. According to the The India
Times, companies must reveal the names of authorised service providers they purchase
bandwidth and internet telephone minutes from. Companies will also have to promise
that they will not use the services of unlicensed foreign providers.
 Skype group (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.
 Competition and alternatives
 Open source alternatives
Ekiga: A free application that supports both H.323, SIP, audio and video. Ekiga
was formerly known as GnomeMeeting. So far works only with various Linux
based systems. No version for Microsoft Windows has been released yet, but
there is a working snapshot available.
Kiax: VoIP application based on IAX.
PSI: The current Beta version has protocol support for Google Talk.
Switchboard: Free VoIP applet which works from within a web browser. Works
on Windows, Mac, Linux, and any other Java enabled platform. No installation
Tapioca: Includes support for Google Talk.
WengoPhone: A free VoIP application based on SIP open standard.
 Closed source alternatives
amiciPhone: A secure peer-to-peer VoIP application
Google Talk: A popular service provided by Google
Gizmo Project: A closed source VoIP application based on SIP open standard and
uses SRTP between clients. Now offering free landline/cell calls to over 60
iCall: A closed source free VoIP application based on SIP open standard and
providing free PC to Phone calling in the US and Canada.
Jajah: Alternative where no headset, no download, no installation and no
broadband connection is necessary. A VoIP call gets activated between two
Secure Shuttle Transport (SST): Free encryption and secure messaging software
including VoIP and video. Works on PCs running Windows 98 or higher.
Raketu: A VoIP service that combines communication, information, and
entertainment. Its integrated multi-messenger allows communication with
contacts from AOL Instant Messenger, ICQ, MSN Messenger, Google Talk,
Yahoo Messenger and Skype.
SightSpeed: Free video and voice calling service supporting Mac & Windows.
Also allows phone out and in calling.
Parlino: A VoIP network based on open standard SIP-protocols, launched by
Vbuzzer: A VoIP softphone and service as well as an active advocator of SIP
VoipBuster: A VoIP application offering 300 minutes per week of free calls to
landlines in many countries, including the EU, USA, Australia, etc.
VoipStunt: A VoIP application offering 300 minutes per week of free calls to
landlines in many countries, including the EU, USA, Australia, etc.
Zfone: A solution of Phil Zimmermann (inventor of PGP) to encrypt VoIP (SIP)
sessions, protocol published as IETF draft. 
TipicIM: A free VoIP application, Videocalling based on XMPP/Jabber and
Speex audio codec support
[ClosedTalk]®: A secure VoIP software free from CE-Infosys for
Business/Personal use. Works on PCs running Windows 2000/XP. [ClosedTalk]"
exposes �man in the middle� attacks by displaying a short security message on
both caller screens for comparison.
BT Communicator: A VoIP service from British Telecom (BT plc.)
 See also
Voice over IP
o Comparison of VoIP software
o Comparison of instant messaging clients
o Comparison of instant messaging protocols
Skype Journal: An independent online magazine about Skype
Nuvvo eLearning Service: an on-demand service with SkypeWeb Presence
1. ^ Jaanus Kase. Skype is expanding engineering to Prague. Skype Blogs.
Retrieved on 2006-12-05.
2. ^ Interview with Jaanus Kase from Skype. KDE News. Retrieved on 2006-06-13.
3. ^ Skype Privacy FAQ. Skype. Retrieved on 2006-12-05.
4. ^ "VoIP suffers identity crisis", The Register, June 15, 2004.
5. ^ Harry Max. Skype: The Definitive Guide. Retrieved on 2006-08-22.
6. ^ Tom Berson. Skype Security Evaluation (PDF). Retrieved on 2006-06-13.
7. ^ Biondi and Desclaux. Sliver Needle in the Skype (PDF). Retrieved on 2006-06-
8. ^ FileMon for Windows. Sysinternals. Retrieved on 2006-06-17.
9. ^ Bruno Giussani. Swiss magazine digs deeper in social blog. Lunch over IP.
Retrieved on 2006-06-17.
10. ^ Fear of a Skype Planet. Paul Kedrosky. Retrieved on 2006-06-17.
11. ^ Skype supernodes sap bandwidth. Computerworld. IDG. Retrieved on 2006-06-
12. ^ Jack McCarthy. China bans Skype. InfoWorld. Retrieved on 2006-06-17.
13. ^ eBay Completes Acquisition of Skype. eBay. Retrieved on 2006-06-17.
14. ^ Skype Launches Next Generation Free Internet and Video Calling for
Everyone. Skype. Retrieved on 2006-06-17.
15. ^ Philippe BIONDI and Fabrice DESCLAUX. Silver Needle in the Skype.
blackhat. Retrieved on 2006-03-02.
16. ^ Bambi Francisco. eBay execs say Skype growing fast. MarketWatch. Retrieved
17. ^ Free calls to all landlines and mobile phones within the US and Canada. Skype.
Retrieved on 2006-06-17.
18. ^ 
19. ^ 
20. ^ 
21. ^ Skype launches free SkypeOut calls within France
22. ^ 8.000.000 online!
23. ^ Introducing Skype 3.0 Beta for Windows
24. ^ 
25. ^ Jaanus. Eight million online. Skype Blogs. Retrieved on 2006-11-08.
26. ^ 8 million onliners. skypenumerology. Retrieved on 2006-11-08.
27. ^ Mathaba.net Who is using Skype?. Skype News. Retrieved on 2006-06-17.
28. ^ What do people put in their Skype profiles?. Skype Journal. Retrieved on 2006-
29. ^ "Executives say China is Skype's biggest market", China View, Xinhua News
Agency, May 5, 2006.
30. ^ International carriers' traffic grows despite Skype popularity. TeleGeography
Report and Database. Retrieved on 2006-12-07.
31. ^ Adding chat styles to Skype. blodspot.com. Retrieved on 2006-06-13.
32. ^ Adium message styles and Skype (1 updates). Soeren Says. Retrieved on 2006-
33. ^ Philippe BIONDI and Fabrice DESCLAUX. Silver Needle in the Skype.
blackhat. Retrieved on 2006-03-02.
34. ^ Pallavi Gogoi. "Skype Under Attack", Business Week, McGraw Hill, June 6,
35. ^ Skype uses peer-pressure defense to explain China text censorship. The
Register. Retrieved on 2006-06-18.
36. ^ eBay Completes Acquisition of Skype. Skype. Retrieved on 2006-06-12.
37. ^ "eBay to buy Skype in $2.6bn deal", BBC, September 12, 2005.
 External links
Official Skype website
Scientific Research on Skype (Reverese Engineering, etc.)
White paper on Skype, focus on supernodes
Skype Security Evaluation by Tom Berson (Anagram Laboratories)
Graze the page of Skype
Paper discussing Skype's internals from a security perspective (Black Hat Europe
2006) - Philippe Biondi & Fabrice Desclaux
Skype, Zennstrom, Friis Et Al Sued for RICO Violations
Kodak Photo Voice for Skype
Skype to Charge for Unlimited Phone Call Plan
Detecting Skype and P2P traffic - A general identification method
Retrieved from "http://en.wikipedia.org/wiki/Skype"
Categories: Cleanup from November 2006 | All pages needing cleanup | Articles with
unsourced statements | Telephony | VoIP software | Free VoIP software | File sharing
programs | Teleconferencing | Groupware | Communication | Collaboration | Instant
messaging | Online social networking | On-line chat | Telephone service enhanced
features | Freeware | Windows instant messaging clients | Mac OS X instant messengers |
Linux instant messaging clients | Web 2.0 | EBay