Motorola RAZR V3 Repair Manual - Page 4

V3-Razr Repair Manual Technology GSM overview Preface This page discusses the GSM mobile telephony system, which is increasingly popular and established throughout the world. The term GSM usually means the GSM standard and protocols in the frequency spectrum around 900MHz. There is also DCS1800 - GSM protocols but at different air frequencies around 1800 MHz - and in the United States, where spectrum for Personal Communication Services (PCS) was auctioned at around 1900MHz, operators using the aptly-named GSM1900 are competing against a plethora of other standards. As a result of this, the original and most widely-used GSM frequency implementation is also becoming known as GSM900, and DCS1800 is also known as GSM1800. However, although the physical frequencies used differ, the protocols and architecture remain the same. System architecture Figure 4 below shows the GSM system architecture, which consists of the switching system, the base station system and the user equipment. Document -ED05020 rev.1.2 This document is considered an uncontrolled document when printed Page 3