Cell Phone Records as Evidence in Legal Cases

Larry Daniel

By Larry E. Daniel

The records kept by wireless phone companies about the use of cell phones are immense and very detailed. Wireless companies keep records about when and where a phone call is made, when text messages are sent and received, and when data is transferred.

All of this phone activity data is available if you ask the wireless phone company to provide it to you, and you are still within the window of time that they keep their records. Unlike many other records, wireless phone records or “call detail records” are not protected by the Stored Communications Act and are not protected by the Fourth Amendment. They can be obtained via subpoena or by request of the account holder via a notarized letter.

In the many investigations we perform, the cell phone device is missing for myriad reasons, leaving any evidence of phone usage to be gleaned from the wireless phone company records. These records are known as call detail records and they are different from phone bills.

A phone bill is only accurate to the minute since the majority of wireless phone companies bill to the next full minute. This means that a phone call that lasts 15 seconds would show 1 minute on a phone bill. A call that lasts one minute and one second will show as two minutes on a phone bill. Also, a phone bill is only going to give you evidence of billable activity. Billable activity does not include outgoing calls that did not connect to another phone, and may not include outgoing calls that connect to another phone’s voicemail.

Call detail records will give you the phone activity duration to the second for most wireless phone companies. Additionally, a call detail record will provide all call attempts whether they connected or not. And if requested, call detail records will contain the cell tower used for each connected phone call.

The call detail records can contain multiple types of records, including voice, text messaging and data transmission activity. The biggest mistake we see in the interpretation of this activity is that data transmissions are the result of user activity. Our firm worked a trucking accident case where the opposing expert was a 20-year veteran homicide detective who advised counsel that data transmissions indicated the truck driver was using his phone at the time of the accident. However, once we explained that data transmissions occur all the time, whether the phone is being used by the person or not, and that it is impossible to determine what kind of data is being transferred, the opposing party dropped the case.

Voice calls are an indication of phone usage by the driver, however, whether or not the phone is being used hands free is impossible to determine from a record. Also, if the incoming call is answered by voicemail can be determined from the call detail record, where on some phone bills, this would not be indicated.

Text messaging is shown in call detail records. However, the content of text messages is not. To get the content of text messages, a request must be made to the phone company within days of the incident. Another misinterpretation that comes up in many of the distracted driving cases we do is that incoming text messages are an indication of user activity. It is impossible to tell from a phone record that incoming text messages are being read by the person with the phone. Outgoing text messages can be an indication that the phone is being used at the time the message is sent, but this is not an absolute as some applications can send message replies automatically if a person’s phone is moving in a car or truck.

Location information stored in call detail records can be used to determine if a phone is near a particular place. For instance, in insurance cases, it may be important to know if someone is near a location when a fire started. Call detail records can allow an expert to determine of the phone was in the general area near the time of the fire, or other incident. We have used this information in cases involving fires, explosions, and hit-and-run auto accidents. In one case we handled, the insured driver in a hit-and-run case claimed to be in Atlanta, Georgia, at the time of the accident that occurred in Birmingham, Alabama. The driver’s call detail records clearly showed the phone near the location of the hit-and-run at the time of the accident.

To get a complete picture of what happened in many cases, getting the call detail records from the wireless phone company is critical.


Larry Daniel is a digital forensics examiner and cellular analyst with Guardian Digital Forensics. He holds eight certifications in cell phone, GPS, and computer forensics, and telecommunications. He has testified as an expert over 50 times in state and federal courts, and is the author of two books, “Digital Forensics for Legal Professionals” and “Cell Phone Location Evidence for Legal Professionals.” His curriculum vitae, references, and testimony experience are available upon request. For more information, email larry@guardiandf.com, call (919) 868-6291 or visit www.guardiandf.com.