On the same day that the state of Illinois sued Facebook over its alleged misuse of data that allowed Cambridge Analytica to download information on more than 50 million users, Facebook confirmed that it had been collecting and storing call logs and text message metadata for millions of Android users.

Last week, one user who downloaded his data to learn what Facebook knew about him in the aftermath of the Cambridge Analytica scandal found that the company had a record of the date, time, duration, and recipient of calls he had made from the past few years. On Saturday, the tech news site Ars Technica published an account of several others—all Android users—who found similar records.

In response, Facebook published a post Sunday denying that it ever logged call or text history without a user’s permission. But it did acknowledge that it was collecting and storing these logs, attributing it to an opt-in feature for those using Messenger or Facebook Lite on an Android device. “This helps you find and stay connected with the people you care about, and provides you with a better experience across Facebook,” the company said in the post. “People have to expressly agree to use this feature.

“We introduced this feature for Android users a couple of years ago. Contact importers are fairly common among social apps and services as a way to more easily find the people you want to connect with.”

Ars Technica refuted their claim that everyone knowingly opted in. Instead, Ars Technica’s Sean Gallagher claimed, that opt-in was the default setting and users were not separately alerted to it. Nor did Facebook ever say publicly that it was collecting that information. “Facebook says that the company keeps the data secure and does not sell it to third parties,” Gallagher wrote. “But the post doesn’t address why it would be necessary to retain not just the numbers of contacts from phone calls and SMS messages, but the date, time, and length of those calls for years.”

On Monday, in response to the Cambridge Analytica scandal, the Federal Trade Commission announced it was launching a probe into Facebook’s privacy practices.