Screen turns off when placing calls

[nihed]

i have c4 duel and i have a problem which is when i make a call or when i receive a call it enter into stand by, even if i push the start button, what should i do? 

[Phy]

Do you experience the same on safe mode?

How to boot on safe mode
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

How to boot on safe mode on Lolipop
1. press and hold the power key
2. once you get the pop up menu 
3. press and hold "power off" 
4. Boot on safe mode should become available

[nihed]

i did what u said but still have the same problem 😕 

[Uliwooly]

@nihed

That seems to be a network issue more than a phone issue.

[nihed]

really! but i have no problem with the network i can receive calls but when i replay the screen turn into stand by 

[Uliwooly]

@nihed

could you post a screenshot?

[nihed]

i can't  

[Uliwooly]

@nihed

How come?

[nihed]

i told you that the screen turn into stand by when i make a call

[Uliwooly]

@nihed

when you say standby, are you referring to the screen being black? if so, does your phone has a protective case or film or glass?