Competition among telecommunications service operators has been increasing significantly. "Quality," where it related to mobile telecommunications services, is an important keyword in the competition. This study aims to determine the effect of interactivity between operators and their customers as well as the influence of interactivity on the service quality of mobile operators. The sub-variables used for the interactivity (as independent variables) include control activities, interactivity responsibilities and non-verbal interactivities information. Quality of service is treated as a dependent variable. Sampling was conducted using the non-probability purposive sampling technique. Regression analysis showed that the quality of service is strongly influenced by the interactivity responsibilities sub-variable. On the other hand, the non-verbal interactivities information sub-variable had the least influence. The results indicate interactivity responsibility is considered to be the variable providing most influence on service quality, while the least influencing variable is the non-verbal information interactivity variable. The determination factor is 52.8%, meaning that interactivity is just 52.8% of the required variables for influencing the quality of services, while the rest, which is 47.2%, is another variable that is not covered in the model.