You can see it from their court filings. I think it's an amazing technical accomplishment that the only information they have stored in the clear under a user's

You can see it from their court filings. I think it's an amazing technical accomplishment that the only information they have stored in the clear under a user's phone number is the last connection date and account creation date. https://www.aclu.org/open-whisper-systems-subpoena-documents https://www.aclu.org/open-whisper-systems-subpoena-documents You can also disable contact backup on Android.