Why not just use appropriate tools for appropriate tasks? Making PSTN private is a battle you won't win because who you speak to is ultimately going to be the w

Why not just use appropriate tools for appropriate tasks? Making PSTN private is a battle you won't win because who you speak to is ultimately going to be the weakest link of any solution, likewise your cellphone itself, and all the infrastructure comms pass through. Secure comms? Matrix protocol. Secure email? Forget it. Secure PSTN? Forget it.