Male midwife toads emit a short, tonal advertisement call. Previous studies have shown that two nearby males engaged in acoustical competition (duet) increase their calling rate. We address the question of whether acoustical competition is expressed in the temporal adjustment of the calls of nearby calling males. One male emits its calls typically immediately after the emission of a nearby male with an approximate phase angle of 80°. Variation in timing of calls is correlated with the size of the calling male (as inferred by call frequency). Playback experiments with females show that the timing of calls between interacting males can influence the choice of a mate. Females prefer duets of males calling with a phase angle of 180° rather than 90° and prefer males responding to calls over males initiating the duets.