People are wondering what, exactly, the social network knows about them. As it turns out, the answer includes data about phone calls and messages. The revelation could make Facebook’s huge data scandal hurt more than ever.

The news: Users have been reporting that personal data held by Facebook shows that the social network has collected metadata about phone calls and text messages on Android devices.

Facebook says: That the logs are “part of an opt-in feature,” adding that it will “never sell this data, and this feature does not collect the content” of calls and messages.

Why it matters: Such statements may not assuage user concerns. A Reuters-Ipsos poll says that just 41 percent of Americans surveyed trust Facebook to obey US privacy laws. Consumers may be realizing that their data has value, and that could upset the ad market that underpins Facebook’s business model.

Regulation incoming? Some tech luminaries are joining Facebook’s own senior team in calling for regulation. Apple CEO Tim Cook says that “some large profound change is needed” in the way user data is handled.

Investigation ongoing: Regulations or not, the wheels of officialdom are now in motion. The Federal Trade Commission explained today that it “takes very seriously recent press reports raising substantial concerns about the privacy practices of Facebook,” and confirmed that it “has an open non-public investigation into these practices.”