The Federal Communications Commission said the agency will investigate mobile carriers’ compliance with rules requiring carriers to fully disclose to consumers how they are using and sharing geolocation data.

“Our mobile phones know a lot about us. That means carriers know who we are, who we call, and where we are at any given moment. This information and geolocation data is really sensitive,” FCC Chairwoman Jessica Rosenworcel said. “That’s why the FCC is taking steps to ensure this data is protected.”

In July, Jessica Rosenworcel asked the 15 mobile carriers including Verizon , AT&T and T-Mobile for information about their data retention and data privacy policies and practices. The FCC released the responses today.