1. A mobile communications device, comprising: a processor coupled to at least one first input that passively collects input data and at least one second input that collects response data based on a challenge; memory, storing program instructions that when executed by the processor cause the processor to calculate a level of assurance (LOA) that a user is in possession of the mobile communications device by: generating a statistical behavioral model based upon the passively collected input data for the user and an artificial neural network providing artificial intelligence (Al) for learning new passively collected input data for addition to the statistical behavioral model; determining an LOA based upon the statistical behavioral model and the passively collected input data from the at least one first input; comparing the LOA with a threshold and based on the comparison: determining that the LOA meets or exceeds the threshold, and as a result of the determining, enabling a mobile device operation without requiring response data from the at least one second input; and otherwise, determining that the LOA does not meet or exceed the threshold and, as a result of the determining, generating the challenge and enabling the mobile device operation responsive to valid response data from the at least one second input device; and generating an authentication token based upon the LOA being above the threshold, the authentication token authorizing a transaction terminal to cooperate with the processor to perform the mobile device operation.