No sound during calls . FaceTime/music/mic works - Repair motherboard?

Hi,

I got a really weird problem with my phone. Ive browsed the internet and really haven't found any information regarding this issue.

As the topic states..

Troubleshooting

- Mic works, tested it by recording something.

- Tested both speakers, working.

- Re-installed several times.

- Got all bars on 3G/4G

Issue

- Upon calls i can't hear anything, same goes for the other party. No sound at all.

The weirdest thing is tho, if i use the keypad and press any given key, like 1,2,3,4 it will be heard in the other end.

But apart from that, no sound at all.

- FaceTime works, no issue when making calls with that.

Sidenotes

- The unit was dropped, cracked display. Replaced the display and got this issue.

- All cables and parts are correctly mounted.

I reckon this aint a software issue anymore, more likely to be hardware. Does anyone know how to repair this? Guess its motherboard related.

Lots of thanks in advance!

Love the site and keep the good work up.

//L.Wac