For text-dependent systems, the speech material that the user must pronounce in front of the system is a priori determined during the registration. While common-password systems have absolutely no flexibility in the choice of the linguistic material, personal-password systems can enable some text customisation, in particular the possibility for the registered user to change his voice password.
For text-independent systems, at least three modes of interaction with the user can be distinguished: text- and voice-prompted systems impose the (unpredictable) linguistic material to the user, whereas unprompted systems use totally spontaneous speech . In parallel with speaker recognition, prompted systems explicitly or implicitly perform some kind of speech recognition in order to check that the applicant speaker has really uttered what he was asked to say.