This thesis would not have become what it is without the help of several people. First of all, I would like to thank my promotor prof. dr. Wim Lamotte for providing me with useful suggestions about the structure and contents of my thesis and for helping me test several VoIP programs.
Special thanks also go to Igor Kalders. Without his help I would not have been able to test my VoIP applications in a situation where there are at least several routers between the communicating parties and where there is less bandwidth available than on a LAN. Although we did not always find a good subject for a conversation, the tests were certainly useful.
Many other students also helped me test these VoIP applications. These are1 (in no particular order): Koen Beets, Kris Luyten, Tom Van Laerhoven, Peter Quax, Daniël Teunkens, Stef Cant, Panagiotis Issaris and Silvio Sawicki.
I would also like to express my gratitude to the whole class for keeping a good atmosphere in our computer room. Without it, this year would not have been this much fun.