I noticed today that my Samsung Galaxy S4 with CM13 (unofficial Kyasu's ROM) called two my contacts itself; those contacts were those which I keep in my blacklist; which was also why I had react to the incident. I have a passlock in my phone so calling itself is not possible without a break into my system. This implies me that my ROM was cracked, and used for own targets. This is the second time, I notice that my phone calls itself; first time, it called my favorite contact one week ago; in the other end, my friend heard only machine/random noise. Therefore, I would like to add additional measures to control the security/privacy of my phone.
How can you prevent your phone calling itself?