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, causes 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 (AI) 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: when the LOA meets or exceeds the threshold, enabling a mobile device operation without requiring response data from the at least one second input, otherwise generating the challenge and enabling the mobile device operation responsive to valid response data from the at least one second input device, and adding recent input data to the statistical behavioral model responsive to receipt of the valid response data, or excluding the recent input data from the statistical behavioral model responsive to invalid response data.