The third-generation technology of UMTS continues to play an important part in the global communication landscape and the delivery of mobile broadband services. In this short course, we aim to provide a comprehensive introduction into UMTS and in so doing, provide an overview of the architectural view of UMTS and explain how it supports circuit switched voice and packet switched data traffic. Mobility is also discussed in addition to how roaming is supported. Finally, interworking with both 2G and LTE will be discussed, with a brief focus on Circuit Switched Fallback.