For phone calls, I wouldn't call it voluntarily. In order to call someone I need to dial a number and to rely on third party infrastructure, such as I have to at least put a receiver on a snail-mail. I believe the reason why past legislature did not have an eye on that is that it was not viable to slurp up this data en-masse. Such as writing down and correlating each mails sender and receiver. This is easily automatable nowadays. I am convinced that we need to fix this unless we want to live in some dystopian future.