How to beef up privacy on i9500?

[orifuel]

At the moment I'm using my first smartphone Galaxy S4 with an extended battery out off mpj, running Android 4.2.2. No complaint of this phone at all. My only concerns is the privacy on the phone. Once I was talking with my friend and soon I was spammed about the topic we were talking about. CREEPY! Anyone else has same experience? And how can I enhance the protection of privacy? Thanks in advanced.

 

[Rukbat]

Don't hold loud conversations where other people can overhear them.

Or if you're really paranoid, don't turn the cellphone on until you get past the moon's orbit.

And don't watch Person of Interest - they use the Hollywood ROM (it only exists in scripts for movies and TV shows). You can clone a phone so that it appears to be a different one. You can't yet turn one phone into an extension of another one.