Iphone call problem

Problem:

Hi, I can make and receive calls but i can hardly hear the person on the other end. Even when the volume is full or on speaker it sounds like they're miles away but they can hear me. Also it always says call forwarding active and i can tap dismiss. What can I do so I can hear clearly?

Solution:

1. First, try restoring it. Plug it in to the computer and Click Restore When it pops up in itunes. Please note that this will destroy all data on the phone.
   If that doesnt work, call apple.