232 CHAPTER 33 Cellular System Evidence and Call Detail Records These and other factors must be taken into consideration and dealt with if an exami- nation of call detail records is to be performed comprehensively and correctly. 33.4 CALL DETAIL RECORDS AS EVIDENCE OF CELL PHONE LOCATION One of the most important things to remember is that a cell phone cannot be located from a historical call detail record. The best that can be done is that the phone can be placed in a general area corresponding to a cell tower that was con- nected to the phone at a particular time when a call was made or attempted. What the call detail record report contains varies by carrier; however, they will usually supply the following information for each call attempt: l l l l l Date: The date the call was attempted or received Time: The time the call was attempted or received Number called: The number called or calling depending on the direction of the call Usage type: Voice, Data, SMS, MMS Call duration: In minutes or seconds Figure 33.8 shows the portion of a call detail record containing the date, time, and number called. This kind of information is part of what is used to perform an analysis of call detail records by providing the timeline information for an incident. Once it is established that the date and times of phone calls in the call detail record correspond with the timeline in a case, the next step is to get the cell tower identifier from the call detail record. Figure 33.9 shows the part of the call detail record that contains the cell tower identification number or CID. Note that carriers use different abbreviations for the cell tower ID. Some use terms like SZR or other designations for the tower IDs. The cell tower ID (CID) in this case is a five-digit number. The first number is the sector of the cell tower and the last four digits are the cell tower ID number. Using this information, a call can be associated with a particular cell tower and sector of a cell tower. This is done by matching the cell tower ID from the call detail record with the cell tower ID on the list of tower locations that should always FIGURE 33.8 A portion of a call detail record showing dates, times, and phone numbers called