This paper verifies that the fundamental frequency (F0) increase/decrease rates series is able to tell apart two types of vocatives in Libolo's Portuguese: initial call; and insistent call. Based on Partition Markov Models, we elaborate a discriminant procedure that let us identify behavior changes in the local variation of the F0 series by type of vocatives. This way we are able to visualize that each individual tends to change its speaking strategy depending on the vocative type. Particularly, the probability of an increase in the ascent rate of the F0 contour tends to be greater in the insistent call productions than in the initial call ones. These results reveal the role of the pitch range as a consistent prosodic parameter to distinguish the context in which two different calls may be inserted.