It is known that nasal consonants and vowels are more effective than other phonemes for human speaker recognition. However, the influence of channel transmissions on the speaker-discriminative capabilities of phonemes has not yet been examined. Specifically, the speech bandwidth has a strong effect on the human speaker recognition performance and also on the speech intelligibility. The phonemes that permit more accurate human speaker recognition are determined in this study by means of a speaker verification auditory test, focusing on the differences in performance when the stimuli are presented to listeners in narrowband and in wideband. The speech intelligibility is also investigated via an intelligibility test employing the same speech stimuli. Finally, the possible relationship between phonemes offering better human speaker recognition and more intelligible phonemes in the transition to an enhanced bandwidth is discussed.