In this paper we expose our present work on a real-time monitoring system of human activities, using only a single cell phone equipped with some particular sensors. This way the monitoring system is reduced to the minimum expression, no especial hardware is required as far as a conventional cell phone will monitor the user. In particular, we expose our progress on a monitoring system devoted to supervising employee’s work on large premises, detecting abnormal behaviours, hazardous situations and managing the corresponding alert procedures.