Dialler does not display on making a call

[Android Question]

I had bought a new handset of Samsung Galaxy Ace an year ago. But now the dialler does not display on making a call.....

 

[quickaudi]

Welcome to the guest questions forum!

Is this after hitting the Call button that your device does this?
Normally, the sensor on the front of the device will use proximity to determine if your face is near the phone. If it sees something, it assumes it is your face and will shut off the screen.
Is your face near the screen? Maybe your hand is covering the sensor or maybe a screen protector is misaligned or a new case is covering it?