Ctc final presentation skype t5_yuzhao li (u3035801)
Made by: Yuzhao Li
How many of you are using Skype,
or have ever used Skype?
Do you know what the VoIP is?
Voice over Internet Protocol
A general term for a family of methodologies,
communication protocols, and transmission
technologies for delivery of voice communications
and multimedia sessions over Internet Protocol
networks, such as the Internet.
People’s voice or
other sounds record
by the computer as
Then the samples
are send as packets
over IP network to
and played there.
Different from traditional Public Switched
Telephony Network, VoIP has several advantages
Better voice quality
A software application
telephone service using
communication over the
Available free for both
PC and Macintosh
platforms as well as
Linux and pocket PC’s
Founded in 2003 by the Swedish entrepreneur Niklas
Zennstro, and a Dane Janus Friis
In October 2005, eBay purchased Skype
In October 2006, Skype 2.0 for Mac was released
In 2009, Skype 4.0 was released
On October 14 2010, Skype 5.0 for Windows was released
with a slew of improvements and feature additions
active user (in millions)
percentage of market
Skype offers a number of features to its users,
a) Rate control mechanism
b) Voice codec
c) Error-resilience mechanism
d) Better relaying mechanism
to go through NAT servers
Can find and locate users
Strong NAT/ firewall traversal capability
Integrated buddy list, presence information, chat, and
Quality of service
Susceptibility to power failure
Still difficult to make a emergency calls
Lack of redundancy
The security issues
MSN sends smaller packets with higher sending rate
MSN has higher variance in packet’s inter-arrival time
while Skype sends packets in a stable fashion
Skype has better performance than MSN in MOS
Skype can increase its throughput to recover missed
data when suffering from higher loss rate, but MSN
Skype has better mechanisms to go through NAT than
Can call any phone, local or
international, not just
Quality of voice
Have many different options
Skype have a lot of impacts on its users, and also
may influenced people’s daily life.
For example, its impact on teaching and learning.
It opens up numerous options to teacher and
students interactions and the Skype offers can
potentially revolutionize the teaching and learning
process. So that teachers can envision students
exchanging ideas, cultures, and information using
the free Skype to Skype feature from one
classroom to another or one student to another.
Weicheng Xiao. (2006). A performance Study of
VoIP Applications: Skype vs. MSN. National
Lani Rexius. (2007). Skype- An Emerging
Technology. London: Oxford University
About Skype. (2010). Retrieved October 26, 2010.
History of Skype. (2010).Retrieved October
26,2010. from http://en.wikipedia.org/wiki/Skype
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