Voice over IP Technologies provides solid technical information on how to successfully design and implement a converged network, combining voice, data, fax and video transmissions into a cohesive networking infrastructure centered on the Internet Protocol. Converged networks, which combine voice, data, fax and video transmissions into a cohesive networking infrastructure -- all centered on the Internet Protocol, or IP -- promise a number of advantages over existing, separate networking environments. But to successfully design and implement a converged network requires expertise on both the voice and data networking sides of the house. Unfortunately, few individuals have these credentials -- either you are a voice networking expert, and familiar with circuit switching and connections between PBXs, or you are a data networking expert, familiar with packet switching and connections between routers and servers. The objective of this text is to bridge the gap between the voice and data networking sides, and provide the reader with the opportunity to fill in their areas of weakness with solid technical information. In addition, this text presents a number of case studies, from architectural, financial and technical perspectives that illustrate real-world applications for these technologies.