Master's Thesis from the year 2016 in the subject Computer Science - Miscellaneous, grade: 1,0, University of Applied Sciences Technikum Vienna (Telecommunications and Internet Technologies), language: English, abstract: Operator-provided voice services will gradually migrate from today's circuit-switched (CS) voice networks to packet-switched IP networks, using Voice over LTE (VoLTE) as the foundation to provide telecom-grade telephony services. In fact, the capability of transporting Voice over IP (VoIP) services along with the provision of high-rate data throughputs, characterizes one of the critical drivers for the LTE development. This thesis presents the first implications of introducing IMS-based VoLTE in Germany, Austria and Switzerland (DACH) from a mobile operator's perspective. Further VoLTE performance aspects such as parameter optimization and HD voice are discussed, thus serving as a basis to then analyze the DACH mobile network test results for 2014 in terms of telephony and data performance. Overall results for a DACH VoLTE trial conducted in the third quarter 2014 complement the analysis.