"Retention Periods of Major Cellular Service Providers," an August 2010 document produced by the Department of Justice, outlines the types of information collected by various cell phone companies, as well as the amount of time that they retain it. On some levels, this is reassuring: Verizon (VZ) is the only company that holds on to text message content, and they erase it after 3-5 days. However, text message details -- the information about who you text with -- is retained for a minimum of a year, with some companies keeping it for up to seven years. In other words, that little back-and-forth you had with Bernie Madoff back in 2007 will be on the books until 2014.
Who Did You Call?
But what about your phone calls? While the content of your calls -- the things that you say -- is not recorded, all of the major carriers hold onto the information about the people you talked to for at least a year, with some retaining it for as long as seven years. And your phone bill, which can be used to check some of your calls, is kept by most companies for at least three years.
Your cell phone can also be used to track you: information about the cell towers used by your phone -- which law enforcement agencies can use to reconstruct your movements -- is held for at least a year, with some providers retaining it indefinitely. On the bright side, a federal judge recently ruled that these cell phone records are private, and can't be released without a warrant, which means that the g-men won't be able to check your whereabouts unless they can demonstrate that your records are "material to an ongoing criminal investigation."
But most companies hold on to phone bills for at least three years, and these, too, could be used to reconstruct some of your calling habits. In this regard, T-Mobile is the most privacy-aware company: it doesn't retain records at all. Sprint (S) and AT&T (T) both keep records for up to seven years.
Who Keeps Your Secrets?
If you're concerned about privacy, the best cellular provider is either Verizon or T-Mobile. Verizon holds on to most records for just a year, and retains your phone bill for a maximum of five years. T-Mobile, on the other hand, doesn't hold onto IP information, bill copies, or text message content, and retains cell tower info for a comparatively short six months to one year. On the opposite end of the spectrum, AT&T is a treasure trove of information: it keeps details about your phone calls and texts for a minimum of five years, and has retained all of its cell tower information since July 2008.
In a broader context, the issue of electronic privacy is currently on center stage. As Wired recently noted, the DOJ document may shed some new light on Senator Patrick Leahy's (D-Vermont) efforts to amend the Stored Communications Act. Currently, the government does not need to show probable cause to access e-mails or electronic information that has been stored on a server for more than six months.
But even Leahy's proposal would not limit government access to cell phone records. In other words, if you need to have a conversation that you'd prefer the FBI not know about, you might want to stick to pay phones!
Bruce Watson is a senior features writer for DailyFinance. You can reach him by e-mail at firstname.lastname@example.org, or follow him on Twitter at @bruce1971.