The Global System for Mobile Communications (GSM) is the foundational standard for second-generation (2G) digital cellular networks. It was developed to provide a unified digital mobile system that facilitates seamless international roaming and secure voice and data services.
Uses modified versions of LAPD (called LAP-Dm) for the air interface and SS7 protocols (MTP) for the network interface. Layer 3 (Network): Divided into three sublayers: GSM – Architecture, Protocols and Services
Often called the core network, it performs call switching and manages subscriber mobility. Key components include: The Global System for Mobile Communications (GSM) is
A permanent database containing subscriber profiles and their last known location. Layer 3 (Network): Divided into three sublayers: Often
Uses the Subscriber Identity Module (SIM) to store unique identity information. Security is maintained through a challenge-response authentication mechanism and over-the-air encryption using algorithms like A5.
A temporary database storing information for subscribers currently roaming in its area.
Includes features such as call forwarding, call waiting, and multi-party conferences.