Ubiquitous computing for context aware system collects information from many static and moving devices as well as sensor integrated objects. To provide valuable services, it is necessary to track the location of the users or objects. There are many possible applications that can apply location-assisted service such as child tracking, supermarket trolley alert system, firefighter tracking and many more. This paper proposed an indoor location assisted device switching for Voice over Internet Protocol (VoIP) application using session initiated protocol (SIP) for Wireless Local Area Network (WLAN) based. We present real test-bed measurements for indoor environment giving the results of the system operation as well as the system performance. The system performance shows excellent accuracy of 1m.