Book excerpt: This book responds to the growing need to secure critical infrastructure by creating a starting place for new researchers in secure telecommunications networks. It is the first book to discuss securing current and next generation telecommunications networks by the security community. The book not only discusses emerging threats and systems vulnerability, but also presents the open questions posed by network evolution and defense mechanisms. It is designed for professionals and researchers in telecommunications. The book is also recommended as a secondary text for graduate-level students in computer science and electrical engineering.