Popular location-based services through smartphones and other portable devices have brought the tracking of user mobility to the attention in wireless community and have increased its importance continuously. Although the incremental development of GPS technology made the measurement of speed and location of the device more accurate, speed itself cannot fully express the mobility and therefore limits its use in Human and Computer Interaction (HCI). HCI makes user-oriented services possible by interacting computing devices with an user through certain types of I/Os such as keyboards, touch pads and various sensors. It is true that the location and speed of user provides fundamental mobility information for service generators in the world of HCI, but now it is time to give a little deeper aspect of giving user mobility beyond the term speed. In this paper, we scrutinize sensing device motility resulted from human motion and its impact on user mobility estimation, called mobility state, in order to provide conceptual and comprehensive means of mobility including speed. Then we propose Device & User mobility Tracking Algorithm (DUTA) that accurately assess the mobility state without incurring unnecessary power consumption.