This paper presents a design and implementation of a location-aware service system, which combines a radio-frequency-based positioning engine and a multimedia human-machine interface (HMI). In this system, a number of Zigbee sensors are deployed for the localization purpose. Users' locations can be estimated according to their received signal strength samples from the Zigbee sensors. In order to improve the positioning efficiency, a hierarchical positioning architecture is proposed. The multimedia HMI is to help users to access the provided services. A speech recognition system is designed as the input of the system and a visualization system has been developed as the output interface of the location-aware system. Moreover, the visualization service is integrated with the Open Service Access (OSA) platform via mobile network systems. The whole system can be directed to future homecare applications.