Calls are not working topic

Hi there,
since i broke my display and replaced it with a new one, i cant use my N4 for calls.
Everytime i call someone, or i get a call, my respondant can hear me, but i cant hear a single word.
When i use my earphones with a microphone it works.

I have to add, that first, the proximity sensor didnt work as well. Everytime i get a call, or call someone, the display was getting dark.
I Fixed it with this workaround.

Does somebody know a fix for that misbehavior?
Or do i have to buy a new phone, when i want to use my phone for calls?

thanks

xda-developers