This book summarizes important developments in telecommunications, including SS7 over IP, with a focus on SS7 network reliability. But why is SS7 network security and reliability so important? An SS7 network outage results in a breakdown of the signalling between the individual nodes of the network, so that the services of the telecommunication network are no longer available for customers. Apart from the tremendous financial damage to the network operator, the social consequences of such a network breakdown cannot be underestimated. It is shown that the problems can be avoided by suitable network planning, i.e., by assuring bidirectionality, loop-freeness, and sufficient node disjoint routes, or the introduction of new transmission and switching technologies based on ATM and IP networks. The book is written for non-SS7 experts and tries to provide more detailed background knowledge about the SS7 network protocols, the problems, and their solution during the specification work.