CallLock is a tweak that locks your iPhone screen during a call. It can be enabled either manually or automatically and will prevent you from accidentally pressing buttons that could dial, mute, hold, or hangup a call by mistake. This is especially useful for people who have a faulty proximity sensor in their iPhone 4. MANUAL MODE: CallLock will override the default action of the Power button during a call to lock the screen instead of the normal end call action. AUTOMATIC MODE: CallLock will automatically lock your screen as soon as a incoming or outgoing call is connected. CallLock is enabled in manual mode by default. To enable CallLock automatically you must turn on the feature from inside your Settings app. No new icons will be added to your home screen. Available on cydia for only $0.99. I just purchased mine.. it works beautifully. Credit goes to BigBoss.