This paper presents an exploratory study of college-age students using two-way, push-to-talk cellular radios. We describe the observed and reported use of cellular radio by the participants, the activities and purposes for which they adopted it, and their responses. We then examine these empirical results using mediated communication theory. Cellular radios have a unique combination of affordances relative to other media used by this age group, including instant messaging (IM) and mobile phones; the results of our analysis do suggest explanations for some observed phenomena but also highlight the counter-intuitive nature of other phenomena. For example, although the radios have many important dissimilarities with IM from the viewpoint of mediated communication theory, the observed use patterns resembled those of IM to a surprising degree.