Handset Problem?

I have a an handset problem. Although it is not so uncomfortable, it is obvious that there is a problem.

When I call someone, my voice goes well to other side. But when I receive a call from someone, every time I have to say "Hello", "Yeah" etc. twice. My initial word does not go to other side.

Is anyone encounter to this problem? If yes, I hope it is a software problem, not hardware.