Table 1 compares the locationing technologies used in our application and the related works described in Sect. 2. ‘‘Place-Its’’ [10] and ‘‘PlaceMail’’ [11] use Bluetooth and AGPS for indoor locationing, respectively. The main problems of using Bluetooth for location sensing are its limited communication range and the limited ubiquity of stationary Bluetooth devices. Wi-Fi APs, however, are ubiquitous and stationary, which are more handily available for location sensing than using Bluetooth. AGPS can achieve acceptable locationing accuracy in indoor environments, but it requires the support from both the infrastructure of cellular operators and the cell phones. Deploying Wi-Fi APs is easier since anyone can set up an AP to be used in their premises, including in the basement of a building which is not covered by the cellular network. Both ‘‘Location Alert’’ [15] and ‘‘Location Based Task Reminder’’ [16] use the LocationProvider Android API [23] to support outdoor locationing and indoor locationing. The accuracy of indoor locationing using the Location- Provider API depends on the density of Wi-Fi AP information collected by Google. In our work, the users can scan the Wi-Fi AP information at the desired indoor locations, which can be either a public location or a private location. In the case of a private indoor location such as a user’s office or bedroom, Google may not have the Wi-Fi AP information at that location. Therefore, using our approach can certainly be more accurate in indoor locationing, which leads to better user satisfaction.