GSM ban đầu được thiết kế như là một mạng thông tin di động toàn châu Âu, nhưng không lâu sau khi khởi đầu thành công của RST ® mạng lưới thương mại tại châu Âu, các hệ thống GSM cũng đã được triển khai trên các châu lục khác (ví dụ như ở Úc, Hong Kong, và New Zealand). Trong khi đó, mạng 373 trong 142 quốc gia đang hoạt động (xem Phần ). Ngoài các mạng GSM hoạt động trong băng tần 900 MHz, cái gọi là truyền thông cá nhân Networks (PCN) và Hệ thống Thông tin. | GSM Switching Services and Protocols . Second Edition. Jörg Eberspächer Hans-Jörg Vögel and Christian Bettstetter Copyright 2001 John Wiley Sons Ltd Print ISBN 0-471-49903-X Online ISBN 0-470-84174-5 12 GSM - The Story Goes On Globalisation GSM is now in more countries than McDonalds. Mike Short Chairman MoU Association 1995-1996 GSM was initially designed as a pan-European mobile communication network but shortly after the successful start of the first commercial networks in Europe GSM systems were also deployed on other continents . in Australia Hong Kong and New Zealand . In the meantime 373 networks in 142 countries are in operation see Section . In addition to GSM networks that operate in the 900 MHz frequency band so-called Personal Communication Networks PCN and Personal Communication Systems PCS are in operation. They are using new frequencies around 1800 MHz and in North America around 1900 MHz. Apart from the peculiarities that result from the different frequency range PCN PCS networks are full GSM networks without any restrictions in particular with respect to services and signaling protocols. International roaming among these networks is possible based on the standardized interface between mobile equipment and the SIM card which enables personalization of equipment operating in different frequency ranges SIM card roaming . Furthermore a more general standardization of the SIM concept could allow worldwide roaming across non-GSM networks. Besides roaming based on the SIM card the MoU has put increasing emphasis on multiband systems and multiband terminals during the last years dualband triband . Multiband systems permit the simultaneous operation of base stations with different frequency ranges. In connection with multiband terminals this approach leads to a powerful concept. Such terminals can be operated in several frequency bands and they can adapt automatically to the frequencies used in the network at hand. This enables roaming among .
