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  • 1. Made by: Yuzhao Li
    Student ID:u3035801
    Skype A case study of VoIP applications
  • 2. How many of you are using Skype, or have ever used Skype?
    Do you know what the VoIP is?
    Warming-up questions
  • 3. 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.
    VoIP
  • 4. People’s voice or other sounds record by the computer as samples
    Then the samples are send as packets over IP network to another computer and played there.
    How does VoIP work
  • 5. Different from traditional Public Switched Telephony Network, VoIP has several advantages
    Cost saving
    Flexibility
    Better voice quality
    Advantages of VoIP services
  • 6. A software application that provides telephone service using VoIP technology facilitating voice communication over the internet.
    Available free for both PC and Macintosh platforms as well as Linux and pocket PC’s
    Skype
  • 7. 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
    History of Skype
  • 8. Usage and market share
  • 9. Skype offers a number of features to its users, such as:
    Features
  • 10. Rate control mechanism
    Voice codec
    Error-resilience mechanism
    Better relaying mechanism to go through NAT servers or firewalls
    Reasons of Skype improvement
  • 11. Can find and locate users
    Highly scalable
    Strong NAT/ firewall traversal capability
    Security feature
    Integrated buddy list, presence information, chat, and audio conferencing
    Highlights of Skype
  • 12. Quality of service
    Susceptibility to power failure
    Still difficult to make a emergency calls
    Lack of redundancy
    The security issues
    Challenges
  • 13. MSN sends smaller packets with higher sending rate than Skype
    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 score
    Skype can increase its throughput to recover missed data when suffering from higher loss rate, but MSN can’t
    Skype has better mechanisms to go through NAT than MSN
    Skype vs. MSN
  • 14. Clarity
    Reliable
    Can call any phone, local or international, not just computers
    Quality of voice
    Have many different options
    Why people use Skype?
  • 15. 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.
    Impacts on users
  • 16. Weicheng Xiao. (2006). A performance Study of VoIP Applications: Skype vs. MSN. National Taiwan University
    LaniRexius. (2007). Skype- An Emerging Technology. London: Oxford University
    About Skype. (2010). Retrieved October 26, 2010. from http://about.skype.com/
    History of Skype. (2010).Retrieved October 26,2010. from http://en.wikipedia.org/wiki/Skype
    References:
  • 17. Thank you for listening!And hope you enjoy this presentation!