During the early 1980s, actually in 1981, to be exact, the first analog cellular telephone was introduced. It was during this time that the Franco-German study of the digital pan-European cellular system began. In 1982 the Conference of European Posts and Telegraphs (CEPT) formed a study group called the Groupe Spécial Mobile (GSM) to study and develop a pan- ¬European public land mobile system. By 1986, a permanent group was formed to create standards for a digital system. A year later, the MoU was signed by over 18 countries. In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute (ETSI), and the GSM name changed to Global System for Mobile communications. A year later, DCS1800, which was edited GSM900, specification was developed and in 1992, Australia was the first non-European country to join MoU.
A GSM network is composed of three main systems, Switching Systems (SS), the Base Station System (BSS), and the Operation and Support System (OSS). The GSM Switching System components include, the Home Locator Register (HLR), the Visitor Locator Register (VLR), the Mobile services Switching Center (MSC), the Authentication Center (AuC), and the Equipment Identity Register (EIR). The Base Station System is composed of the Base Station Controllers (BSC) and the Base Transceiver Station (BTS). The Operation and Support System (OSS) offers cost-effective support to customers and provides network overview and support maintenance activities. It also oversees the proper operation and setup of the network. The other functional components of the OSS include, the message center (MXE), the mobile service node (MSN), the gateway mobile services switching center (GSMC), and the GSM interworking unit (GIWU).
While the GSM network is composed of these three main systems, it can be divided into three broad parts. The first part, the Mobile Station, is carried by the subscriber (Mobile Cell Phone); the second part, the Base Station Subsystem, which controls the radio link with the Mobile Station; and the third part, the Network Subsystem, which is composed of all of the switching system components mentioned above.
