http://nguipxnkrp3qrzrlduhsatpcpwehnblzmlkc5ifiumxq4z5jlh4lwvid.onion/os_archive/os_OPSEC_357.html
Using electro-mechanical devices over phones with microprocessors / digital controllers is simply to remove a hacking vector whereby a hacker can bug your entire house reversing the phone from a communication tool into a surveillance device. Stick to lawful non personal, business and fact relaying only conversations over the telephone, (ordering takeout, calling the government, job interviews, etc).