Abstract: A system for authorizing access to a service by a mobile computing device. The mobile computing device, which is identified by a mobile device identifier, requests authorization to access the service from an application, which has an application instance identifier. A telephone call setup message, which signals a voice call request, is received by the mobile computing device. The mobile computing device disables user interface or notification features of the device prior to receiving the telephone call setup message, and the telephone call setup message is terminated before a voice connection is established with the device. After receiving the telephone call setup message, the mobile computing device sends a communication that causes an association to be made between the mobile device identifier and application instance identifier, enabling authorized access to the service by the device. The mobile computing device then re-enables the user interface or notification features.