Today, the American Civil Liberties Union (ACLU) published the 2010 'data retention chart' received from the U.S. Justice Department by taking out a freedom of information request.
The document shows which mobile networks in the U.S. hold customer data, in what quantity and for how long -- ranging from the content of text messages, to recipients of phone calls, as well as Internet-browsing related activities.
Used to "advise law enforcement agents seeking to obtain cell phone records", it shows how long the six major cellular networks in the country -- Verizon, T-Mobile, AT&T and Cingular, Sprint, Nextel and Virgin Mobile -- hold your personal data for, for use by law enforcement when the data is requested.
Due to the array of lengths of time, it can be assumed that the cell network providers determine their own lengths of time for which data is retained, as opposed to any government or law enforcement issued guidance.
Looking closely at the document, it is clear a disparity arises between the networks, with Verizon, the largest network in the United States, retaining data for the longest.
Some of the most significant findings from this freedom of information request includes:
Verizon is alone in the cell network community in that it holds onto the content of text messages for 3 to 5 days. The company also logs your Internet-browsing history for 1 year, whereas other networks either don't, or hold it for a significantly shorter length of time.
AT&T and Sprint on the other hand holds onto copies of contract bills for 5 to 7 years, and 7 years respectively.
T-Mobile holds onto who you have called, who has called you and other call detail information for 2 years for pre-paid customers, and 5 years for contract customers.
Another feature of this request was cell-site tracking data, specifically in how cell networks track your location data cross-country. Verizon holds onto the data on a rolling yearly basis, T-Mobile holds onto the data for "a year or more", Sprint for up to two years, while AT&T holds this data indefinitely as of July 2008.
The "Retention Periods of Major Cellular Service Providers" can be found here [PDF].