Report: The subscriber data telecom companies collect and how long they keep it

Just what kind of data are U.S. cellular services companies collecting about their customers and how long are they keeping such potentially sensitive information? More important, can law enforcement access your wireless phone data without a warrant?

A recent report from Wired, based on a single-page Department of Justice document specified for "law enforcement use only," suggests that the police have access to a wealth of data from mobile phone users in the U.S.

According to the DOJ's document, "Retention Periods of Major Cellular Service Providers," which was obtained by the American Civil Liberties Union of North Carolina under a Freedom of Information Act, the four major cellular service providers can collect subscriber data and store it for years.

AT&T, for example, keeps details about text messages sent to and from its customers' cell phones for up to seven years. But according to the DOJ document, only Verizon keeps the actual contents of the messages—for up to 5 days.

Retention of cell-site data (information that tracks your mobile phone's connections to specific towers in a cellular network at any given time) also varies among carriers. T-Mobile keeps such information for four to six months, Verizon for 12 months, Sprint for 18 to 24 months, and AT&T for 3 years—or more.

Privacy advocates such as the ACLU and the Electronic Frontier Foundation (EFF) say the document, dated August 2010, reveals the kind of data that law enforcement can obtain. And more disturbing, advocates warn, the police can obtain such carrier records without a court-issued search warrant, because the data isn't protected by the Electronics Privacy Communications Act—a law written nearly 25 years ago, prior to the dominance of cell and smart phones.

Kevin Bankston, a staff attorney with the EFF, told Wired:

I don't think there there is anything on this list the government would concede requires a warrant. This brings cellular retention practices out of the shadows, so we can have a rational discussion about how the law needs to be changed when it comes to the privacy of our records.

Which Telecoms Store Your Data the Longest? Secret Memo Tells All [Wired]
Retention Periods of Major Cellular Service Providers (PDF) [US DOJ via Wired]
Secret memo reveals which telecoms store your data the longest [Ars Technica]
Privacy & Civil Liberties: Electronic Privacy Communications Act [US Department of Justice]
Petition to Upgrade the 1986 Electronic Communication Privacy Act [The Electronic Frontier Foundation]

—Paul Eng