This document provides a summary of the history and architecture of GSM cellular networks. It discusses the evolution from early analog cellular networks to digital GSM networks. Key aspects of GSM include: - GSM uses TDMA and FDMA to allow multiple users to share frequencies and increase network capacity. - The core network components are BTS, BSC, MSC, HLR, VLR, and AuC which manage radio resources, switching, authentication, and subscriber location. - GSM operates in different frequency bands including 900MHz, 1800MHz, and 1900MHz and uses coding to digitize voice into 13kbps traffic channels.