1. A method of performing speaker recognition, the method comprising: collecting representations of voice characteristics, in association with corresponding speakers, the representations being generated by a deployed voice-based interactive system; updating system-level parameters of a classifier used in speaker recognition, based on the representations collected, the representations collected being indicative of inter-speaker and intra-speaker variations in voice characteristics, the system-level parameters updated to improve distinguishability between different speakers by maximizing inter-speaker variations while accommodating intra-speaker variability, wherein updating the system-level parameters of the classifier includes updating the system-level parameters each time a given number of successful identifications of at least one speaker is achieved; and employing the classifier, with the corresponding system-level parameters updated, in performing speaker recognition.