A method is disclosed for blocking a cloned mobile device by a processor of a network. The processor receives a first registration from a first mobile device at a first location. The first registration includes a device identifier and a phone number. The processor then confirms that a second registration from a second mobile device at a second location includes the device identifier and the phone number and calculates a first fraud score for the first mobile device and a second fraud score for the second mobile device. The processor then determines that the second mobile device is the cloned mobile device, when the second fraud score exceeds the first score, and blocks the cloned mobile device from registering on the network.