iPhone X IPhone X lags during calling

[adamsx]

Hi everyone,
I have na IPhone X 2 weeks now and I have na annoying problem.
When someone is calling to me the IPhone is vibrating but person who is calling appears after about 4-5 seconds.
IOS is 11.2.1.
The problem disappears after turning of the IPhone X.
Can U Help me with it?

 

[gahig ulo]

maybe remove the case if you have one on or restart your X and tried calling it after

 

[adamsx]

Why I should remove the case?
I have na oryginal silicon case.