What are Call Detail Records?

Call Detail Records (CDR) are records which provide details concerning individual calls made by a phone. CDRs were around prior to cellular technology. Traditional landline phone companies maintained and provided CDRs to their customers for billing purposes. There is no difference with Cellular telephone companies. CDRs are maintained for billing purposes; however, most cell phone plans include unlimited minutes, text, and data. Cellular service providers maintain not only detailed billing records, they maintain specific detailed information concerning every voice, text, and data communication to/from the individual cell phone. The information stored is different for each service provider and is provided to law enforcement (via a warrant) in different formats. The data provided could be different depending on what is requested in the warrant(s).

A call detail record could provide just basic information; who call who and for how long. Or, it could be very detailed to include every cell tower and antenna used during the communication. Some service providers will even provide network data which goes beyond call detail records and provides location information. This information is sometimes referred to as PCMD (Per call measurement data) or NELOS (network event location system) with AT&T. There is some debate as to how accurate and reliable location data is.

There could be a great deal of information obtained within call detail records if analyzed by an expert. Having an investigator with little or next training or experience review CDRs could result in evidence being overlooked. Also, introducing CDR evidence in court with a non-expert witness could result in a judge or jury not giving the testimony the credibility it deserves.

When working a case that involves cell phone records, or call detail records (CDR) as they are referred to by service providers, you should obtain a qualified expert to review the records and so you can adequately challenge their expert.

Mark Pfoff is a court qualified expert in call detail records analysis and cellular technology. He has provided advisory guidance to legal counsel prior to and during many court proceedings.