The proper use of the rooms on a university campus has become a priority, not only because of the situation in which we find ourselves but also because of the need to optimize the use of educational infrastructure and reduce operating costs. For this reason, the use of the Internet of Things in the development of reservation systems and monitoring of the occupation of spaces, including an adequate management system for mobile devices is essential. In this work, a system has been developed that allows to visualize the occupation of classrooms on a university campus. The necessary information is obtained from the Google Calendar API and displayed on an Android tablet located outside the room. The Android application has been developed using Flutter, and Firebase Realtime Database and Firebase Storage have been used for data storage and synchronization. Also, as part of the system, a web application has been developed to manage the information stored in Firebase and a mobile device management system has been implemented to keep track of the tablets used, their updates and usage restrictions. The system was deployed on a cloud infrastructure using Google Cloud and Amazon AWS to reduce investment costs.