Phone keeps turning off and on, don't know how to stop it

[Melodii]

So regularly, when i call someone on WhatsApp, my phone would turn off and on over and over again on the ringing screen. It has stopped for a while but it usually keeps coming again, please help me solve this. 

[BandOfBrothers]

Is this only happening with WhatsApp calls ? If so try Settings > Apps > WhatsApp > Storage > Clear Cache > to see if that helps.

A more broad option is > Clear Cache Files from the phone's System Partition Section  > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too. 

Another further option is to check the permissions in the WhatsApp App.

Then uninstall from your phone and then also from your MyLibrary in your Playstore and then re download a fresh copy of WhatsApp from your Playstore.

If I can be of any further help then please don't hesitate. Take care.  😎 

[Melodii]

Thank you!