The invention relates to a method for providing mobile communication terminal location data. In the method, radio signal is received from a beacon in a wireless local area network. Next, beacon identification data that identifies the beacon is derived, based on the received radio signal. The identification data is transmitted to a server. Beacon location data is then provided by and received from the server. Mobile communication terminal location data, particularly presence data that indicates that the mobile communication terminal is in the vicinity of the beacon, is derived from the beacon location data. Upon such detected presence, an additional application process is advantageously executed. The method is executed by a processing device in a subscriber identity module that is included in the mobile communication terminal, thus achieving hidden operation and portability. The invention also relates to a subscriber identity module and a system operating in accordance with the method.