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Introduction

1.1 AboutThis Book

Someone who wants to get to know the customs of a country freąuently receives the advice to learn the language of that country. Why? Because the dif-ferences that distinguish the people of one country from those of another are reflected in the language. For example, the people of the islands of the Pacific do not have a term for war in their language. Similarly, some native tribes in the rain forests of the Amazon use up to 100 different terms for the color green.

The reflection of a culture in its language also applies to the area of com-puters. A closer look reveals that a modern telecommunications system, like the Global System for Mobile Communication (GSM), is nothing morę than a network of computers. Depending on the application, a language has to be developed for such a Communications network. That language is the signaling system, which allows intersystem communication by defining a fixed protocol. The study of the signaling system provides insight into the internal workings of a communication system.

The main purpose of this book, after briefly describing the GSM subsys-tems, is to lay the focus on the Communications method—the signaling between these subsystems— and to answer questions such as which message is sent when, by whom, and why.

Because it is not always possible to answer all ąuestions in a brief descrip-tion or by analyzing signaling, details are covered in greater depth in the glos-sary. Furthermore, most of the items in the glossary contain references to GSM and International Telecommunication Union (ITU) Recommendations, which in turn allow for further research.

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