receiving one or more spoken utterances from a user at the device;

recognizing a phrase corresponding to said one or more spoken utterances;

identifying a biometric voice print from the one or more spoken utterances of said phrase;

verifying a location of said device;

determining a device identifier associated with said device;

authenticating said user based on the phrase, said biometric voice print, said location, and said device identifier;

establishing a connection to at least one authentication server;

sending a user profile to said at least one authentication server;

comparing said user profile with a plurality of reference profiles stored on said at least one authentication server;

upon recognizing the phrase, evaluating one or more vocal tract configuration differences between said spoken utterances;

matching one or more vocal tract shades of the plurality of reference profiles based on said vocal tract configuration difference;

determining at least one formant frequency;

determining at least one anti-formant frequency;

evaluating a difference between the formant frequency and the anti-formant frequency for characterizing one aspect of a natural change in a vocal tract configuration; and

determining if the user profile matches one of the plurality of reference profiles for authenticating said user,

wherein a user profile includes at least one of a phrase, a biometric voice print, and a device identifier.