Why can't I hear the other person speaking or speak to them

I have been facing a really weird problem with my iPhone 5S, when ever I make a call or get called I can’t hear the other person talking and they can’t hear me either. Using the speakerphone also does not work. But calling on What app, Skype and other apps work fine, just the phone app doesn’t work.

I have reset my iPhone to factory settings already, but problem keeps happening.