Can't see "end call button"

[Droid mini user]

When I make a call on my Droid mini I cannot see an end call button. Therefore if someone doesn't answer and t goes to voicemail or its a service that continues to call and i want to hang up...I CAN'T! I even move it away from my ear and it won't end. Is there a setting I need to fix or is something else wrong. My Otter Box has a hole for the ear piece to be visible too.