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.

1. GSM Security Overview (Part 1) Wireless telephone history

4. But what’s cellular? HLR, VLR, AC, EIR MSC PSTN BS

13. GSM Overview