Figure 1

Snapshots of all four possible ways of interaction: (A) male to male, (B) male to female, (C) female to male, and (D) female to female, are shown by considering only calls of duration more than one minute and caller and callee ages from 20 years to 70 years. For given age and gender of callers, the calling probability is calculated as the ratio between total number of calls to callees of specific age and the total number of calls to all callees of ages between 20 and 70 years