No ear volume or speaker volume on calls only

Hi Guys,

My nephew gave me his iphone 4 to look at.

During phone calls there is no audio via the earpiece speaker nor the loud speaker via speaker phone.

Using Skpye, viber etc the audio works via the ear and the loud speaker.

The parts in the phone are all genuine, it just stopped working one day.

I order a replacement spear and replaced it however the issue is still there.

I took the board out of the housing and put it into another iphone 4 housing again with all working legit parts.

Issue is still there.

I have tried restoring the phone from backup and also as a new iphone.

Issue still there.

I cannot quiet get my head around this one? Anybody experienced anything like this before?