The 3GPP Mobile Systems Overview course describes four generations of 3GPP systems from the voice-centric GSM via UMTS to later developments such as high-speed Mobile Broadband, LTE, IMS, VoLTE and the emerging 5G System. All topics are presented in a comprehensive – yet easily understandable – way. Essential subsystems, nodes and procedures are described. Basic traffic cases are used to demonstrate the function and architecture of the systems.