Cell phones

Sometimes when I think about cell phones I get a little scared. Has anyone ever been talking on the phone and then heard someone elses conversation? I think that is kind of nerve wracking. If i can hear them can someone else hear me? it just makes me think about technology and who comes up with all of these inventions. I mean dont get me wrong I love using technology it is great, but its weird. I always think someone out there knows every little thing about my life.