Home ยป Which of the following known as the oldest phone hacking techniques used by hackers to make free calls? Cyber Security & Cyber Crime MCQs Which of the following known as the oldest phone hacking techniques used by hackers to make free calls? April 21, 2022 29 Views Q. Which of the following known as the oldest phone hacking techniques used by hackers to make free calls? A. Phreaking B. Phishing C. Cracking D. Spraining Answer: Phreaking