To enter the engineers code go to phone and dial pad and enter the code.
You are now in engineer mode with the top tab telephony.
swipe across until you get to hardware testing.
you will see the drop down menu for receiver, hac, headset, speaker.
select either receiver or speaker
manually change UL gain to say 240.
scroll down the screen and hit the button Set.
go back using < key.
then select voice again just to check the setting for UL gain has changed
then press home and test by ringing someone or receiving a call.
Please let me now if the above has helped.
I have the same problem with the phone speaker. I also tried the "engineers code" method by adyleigh but no luck. My problem is whenever i make a call or someone else calls to me, the voice from my phone is very low. I have to turn on the speaker so i can hear the voice. But for the person who calls dont have any issue hearing my voice; so the mic for my phone is still ok. I need your help on this issue.