All of those questions, messages, and stern commands that people have been whispering to Siri are stored on Apple servers for up to two years, Wired can now report.

Yesterday, we raised concerns about some fuzzy disclosures in Siri's privacy policy. After our story ran, Apple spokeswoman Trudy Muller called to explain Apple's policy, something privacy advocates have asking for.

This is the first time that Apple has said how long it's keeping Siri data, but according to Nicole Ozer, the American Civil Liberties Union lawyer who first brought these Siri privacy questions to our attention, there's still more that Apple could do.

According to Apple's Muller, the company takes steps to ensure that the data is anonymized and only collects the Siri voice clips in order to improve Siri itself. "Our customers' privacy is very important to us," she says.

Here's what happens. Whenever you speak into Apple's voice activated personal digital assistant, it ships it off to Apple's data farm for analysis. Apple generates a random numbers to represent the user and it associates the voice files with that number. This number – not your Apple user ID or email address – represents you as far as Siri's back-end voice analysis system is concerned.

Once the voice recording is six months old, Apple "disassociates" your user number from the clip, deleting the number from the voice file. But it keeps these disassociated files for up to 18 more months for testing and product improvement purposes.

"Apple may keep anonymized Siri data for up to two years," Muller says "If a user turns Siri off, both identifiers are deleted immediately along with any associated data."

But Nicole Ozer says Apple should go further. She'd like to see Apple link to its Siri Privacy policy on its Siri FAQ so that consumers can figure out what's going on before they buy an Apple product. Right now, you can only find it within the Siri Settings section of your iPad or mobile phone.

"There is no good reason for Apple to not include information about privacy practices on their Siri FAQ page," Ozer said in an email message.

Also, even if the Siri data is not linked directly to users, people should be careful about what they say to their personal digital assistant. Transcripts "of what you say to Siri could reveal sensitive things about you, your family, or business," she added. "Siri works for Apple, so make a note to yourself to really think before you speak."

Correction: This story originally misidentified Apple's spokeswoman. Her name is Trudy Muller.