Penetration of high-speed mobile data services including social media and video services has been significantly increased across the globe due to fast development of mobile network and smartphone technologies. A similar trend has also been seen in Ethiopia mainly due to large mobile network expansion projects of the sole incumbent operator ethio telecom, particularly for Universal Mobile Telecommunications System (UMTS) network. To achieve a successful business, mobile operators need to continuously monitor satisfaction of their customers and the quality of their networks to take timely marketing, network optimization and other relevant decisions. While traditionally the focus has been towards network Quality of Service (QoS), operators recently also provide attention to the aggregate user quality perception – Quality of Experience (QoE). Yet, a combined quality analysis for mobile networks in Ethiopia, particularly for the popular UMTS data service, has not been performed. In this thesis work, the detailed QoS and QoE evaluation for Addis Ababa UMTS data service including both network quality perspectives and user side perception focused on selected enterprise customers are presented. Assessment of quality monitoring process in ethio telecom has been done before conducting the evaluation on QoS and QoE. The evaluation is made based on download throughput, upload throughput and latency quality metrics collected from network management system (NMS), indoor walk test, crowdsourcing test using RTR-NetTest tool and contextually formulated survey questionnaire. In general, achieved throughput and latency results show that both QoS and QoE are not good and there is dissatisfaction of customers. For instance, the average download throughput results are 0.57 Mbps from NMS, 0.86 Mbps from indoor walk test and 2.53 Mbps from RTR-NetTest. These quantitative results are reflected in the perception result of the participants where a Mean Opinion Score value of 2.65 for the satisfaction of downloading files or video/music is achieved