Service-oriented computing is the computing discipline that views services as the fundamental elements for developing applications and solutions [PAP03]. This book is about orchestrating services that execute across different networks and answering the challenges such an arrangement inevitably poses. Specifically, we explore service-oriented computing in the context of enabling cross-network services between two communication networks: the Internet and the public switched telephone network (PSTN). We use the term
in this book to encompass two aspects of the switched telephone network: wireline networks and cellular networks. Unless specified otherwise, the term will refer to both aspects of the switched telephone network.