Screen blackens on Galaxy during call

[GalaxyJake]

My Galaxy S II has the annoying habit of having its screen go into idle or sleep mode and then blacken when I'm on a call. I want to have the "Phone" screen showing up at all times when I'm on a call, so I can access the speakerphone, etc. Is there a way to "lock" the screen in "Phone" mode when I'm on a call?

[greenman]

Go into Settings >Call and turn off proximity sensor.