This text offers a comprehensive treatment of the entire GSM network and the signalling methods of its terrestrial interfaces. It introduces all the interfaces between the GSM subsystems, starting with the Abis- and Air-Interface and continuing on to VLRs, HLRs and MSCs within the NSS. The reader learns about the various signalling standards or methods used in GSM, including TCAP and MAP, and how to apply this knowledge when working with GSM networks. The glossary explains abbreviations, terms, parameters, counters and messages frequently encountered when working with GSM. In addition, it features numerous figures, tables, lists, statistical formulas, real-life examples and everyday comparisons.