Telecommunications networks are being radically transformed in many ways. One of the most important transformations is from being closed systems that are owned, operated, and programmed by a few companies, to being open systems that allow, in principle, anyone to develop new programs and offer new services to users.
This transformation represents a major development in the evolution of networks. If fully or even substantially completed, it will be a key to realizing the tremendous potential of telecommunications and the Internet today. This ongoing transformation is the context and motivation for this book.

[...]

Finally, this book is about APIs for converged networks. Converged networks consist of—and can take advantage of—multiple underlying technologies, such as packet networks (like the Internet), circuit-switched networks (like the telephone network), and wireless networks. The promise of converged networks lies not in their ability to interconnect different networking technologies per se, but that with the help of open, standard APIs, they can provide a wide range of connectivity options and innovative and advanced services to end users.