My friend had a work phone & was told that she could make personal calls/texts on it. She had a job in a field that had federal oversight, and she said there was no way she would ever make a personal call on that phone … it could be subpoenaed, and even if nothing she said was an issue, she absolutely did not want the government to have contact information for any of her friends or family. At the time, I thought she was a bit paranoid, but now I understand.
In my last job, my coworker and I dealt with a lot of sensitive issues. We never wrote anything down on a work computer or via a work email address. We would only discuss things face to face, or if that wasn’t possible, by talking on our personal phones (never text or personal email). We had situations where all documentation was subpoenaed, and we were always glad that we didn’t leave a paper or electronic trail that included things we wouldn’t want others to see.