Why does my phone keep restarting when trying to dial any number? My Yureka Cyanogen restarts whenever I try to make a call. When I dial a number it restarts but not when I receive it. 

What could be the problem and how to solve it?
Looks like you have applied any buggy CM themes.Use default theme and checkout. Try to clear the data of that particular phone app. Most of the time it happens when we replace CM phone app by google phone app during the open gapps installation. use another phone app
A dirty flash can be helpful. Also which version you are running. Is it nightly or stable version?