I needed to do what I call a "traffic analysis." The process begins with looking at the call detail records (CDRs) of one person whose phone number you’ve identified and pulling information from those records. Whom does he call frequently? Who calls him? Does he sometimes make or receive a series of calls in close succession to or from certain people? Are there some people he mostly calls in the morning? In the evening? Are calls to certain phone numbers especially long? Especially short? And so on.