Abstract: The present invent ion relates to a mobile advertisement system (100), a method and an application server (40) used to prevent user equipments (10) hosting a forged client 5 application or client software to get access and to hold an external data network connection. According to the present invention, an application server (40) is adapted to receive from the core network (20) of the advertisement system (100) a message comprising an end user identification number (e.g. MSISDN). The application server is further configured to trigger an advertisement confirmation timer which expects to receive an advertisement display confirmation message from the client of the user equipment (10). Upon the timer expiring, the application server (40) request the core network (20) to disconnect the user equipment thereby preventing the user equipment hosting a forged client application to get access and to hold a external data network connection.