]> 2006-11-10T13:00:00-05:00 2006-11-10T14:00:00-05:00 In this talk, we use the Call Detail Records of a mobile operator from four geographically disparate regions to construct call graphs, and analyze their structural properties. Our findings provide business insights and help devise strategies for Mobile Telecom operators. Another goal of this paper is to identify the shape of such graphs. In order to do so, we extend the well-known reachability analysis approach with some of our own techniques to reveal the shape of such massive graphs. Based on our analysis, we introduce the Treasure-Hunt model to describe the shape of mobile call graphs. ]]>