How long does Apple keep Siri user data? Two years.

But Apple says that six months after a Siri request or command is made, the phone number of the user is 'disassociated' with the audio clip in question. 

According to the privacy agreement for Apple's Siri service, Apple is authorized to collect and store data from user commands. But how long can Apple keep that data? This was the question posed earlier this week by a lawyer for the American Civil Liberties Union, who registered her concerns in an interview with Robert McMillan of Wired.

And now we have an answer, courtesy of Apple spokeswoman Trudy Muller: two years. "If a user turns Siri off, both identifiers are deleted immediately along with any associated data," Ms. Muller told Wired.

In addition, she explained, six months after you issue a command or query to Siri, your phone number will be "disassociated" from the audio recording (although it will not be fully scrubbed from Apple servers for another 18 months after that). Apple says it uses all that data to help improve the Siri platform, and to better understand how consumers use the service.  

As Darrell Etherington notes over at TechCrunch, Apple isn't exactly doing anything new here. 

"The bottom line is that if an app or service requires a data connection, in all likelihood there’s a back and forth transmission of information going on, and if privacy is one of your top-of-mind concerns, you should be cautious in any such situation," Mr. Etherington writes. "Apple’s policies with Siri seem no more or less egregious than any other, but it is nice to see the company spell it out in no uncertain terms." 

Monitor readers may remember that back in March of last year, IBM revealed that it had banned employees from using Siri on company iPhones. The reason was simple: IBM has no control over (and not much information on) what Apple does with the data.  

"We're just extraordinarily conservative," an IBM exec said at the time. "It's the nature of our business."