<p>The virtual classroom service system was developed as a system-of-systems that integrates three key virtual class service systems: teaching administration, course content management, and video meetings. After being used to assist online training, it is vital to assess the level of user acceptability of the technology utilized. UTAUT was used as a framework for measurement. In addition to utilizing the original construct from this framework, this study introduces the Technology Integration (TI) construct as a novelty that meets the characteristics of virtual classroom service systems as a system-of-system. The system acceptability assessment included 55 respondents who had actively used the system in online training activities. They completed a questionnaire based on a hypothesis model created for the specified UTAUT construct. Furthermore, the PLS algorithm, in conjunction with Smart PLS 3.0 software, is used to process questionnaire data from respondents. According to the algorithm calculations, the hypothesis model designed has an explanatory power score above 0.6 for each dependent variable. This suggests the model can make accurate predictions. Furthermore, construct TI has the highest influence among other constructs in determining the user's intention (0.491) and actual use (0.423) of the virtual classroom service system. These findings can be useful for educational institutions that use virtual classrooms. In addition, various development recommendations are presented to serve as a valuable resource for future enhancement.</p>