I have a brand new S5 neo giving me the same problem. The only way I could get rid of the echo on the other end was to turn on the speaker phone, or plug in a headset. I tried just about everything, even Samsung's technical services without much luck, other than sending it down east for an evaluation. I never could find a noise reduction option on my phone setup, but, I did have a "hearing aid" assist thing which I turned off .... miraculously, it worked and all is well. I figured it would be something simple and it was. Good luck.