I would recommend books, sample programs, tutorials. You should check out the followings: - http://stackoverflow.com/questions/194812/list-of-freely-available-programming-books (Here you can find a lot of programming books) - http://www.voip-sip-sdk.com/p_267-c-net-softphone-voip.html (A sample program in Visual C++.Net but there are other ones as well) - http://www.w3schools.com/ (Online Webtutorials) Hope this information will help you. Good luck for your future plans.