Handles authentication, security, and location tracking.
Primarily high-quality digital voice calls and SMS. GSM – Architecture, Protocols and Services
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. Handles authentication, security, and location tracking
Handles the radio link with mobile devices. It includes the Base Transceiver Station (BTS) , which contains the radio transmitters and receivers, and the Base Station Controller (BSC) , which manages radio resources and handovers for multiple BTSs. and the Base Station Controller (BSC)
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: