Why Does My iPhone 6 Earpiece Won't Work After Making A Call Unless I Use My Earphones Or Speaker Mode? Here's The Fix.
When you make a phone call, you get no sound from the earpiece? That can be a hardware issue, but first try to do a restart. If does not solve the problem, try restore to rule out software problems.
If this does not fix the problem, then it’s most likely a hardware issue. Apple can help you find and fix the problem or it may be covered if you have AppleCare.