What Is Call Detail Record (CDR)?

Call Detail Records (CDR) are like little pieces of evidence. They can be used to convict you or absolve you. They can implicate you or exonerate you. They can incriminate you, or they can clear your name. They are tiny and insignificant on their own, but when combined with other evidence—like other CDRs and the testimony of witnesses—they can make all the difference in the world. A telephone exchange creates CDRs as part of a phone call's record-keeping process. Each time someone calls your exchange, it records the call's duration, what numbers were dialed, who placed the call, and who answered it. It also holds this information for all outgoing calls from your phone line. These records are stored in a database for later retrieval by law enforcement officials who need them as part of an investigation into possible criminal activity involving phone lines at your location, elsewhere around town, or across state lines (or even internationally). The telephone system is a complicated, interwoven web. Telephone exchanges' billing systems create the CDRs. The transmitter exchange saves the CDRs until the call ends. Computer networks transport CDRs to a central point. X.25 links are used worldwide for transporting CDRs. It's like this: imagine you're at a party and want to talk to your friend across the room. You can't just yell over all the other conversations! Instead, you yell through someone already talking to your friend—and then they pass on your message until it reaches your friend. This is how telephone networks work: they have to pass information from one place to get it where it needs to go. It's time to get honest about CDRs. CDRs can be billed. They can be used for support. They can help us estimate the amount of route traffic. But did you know that CDRs are also the foundation of all things? It's true! The universe is built on CDRs: every second, every moment, every millisecond—thanks to CDRs. Without CDRs, we wouldn't even exist! Think about it: they're what keep our phones connected so we can communicate with one another and have human interaction. If you think about it, without them, you'd never be able to call your mom and tell her how much you love her.