InCall Lock will temporarily disable Send (aka Talk, Green) and End (aka Red) hardware buttons when you receive an incoming call in order to prevent accidental call pickups/rejects while you are pulling your device out of your pocket. All other hardware buttons are untouched.

After you answer/reject your call the application will release the buttons, so you will be able to hang up, put calls on hold etc. using hardware buttons normally.

The application, after being launched, will remain resident in memory but will not use any CPU cycles at all as it relies on WM Notification system and doesn’t do any polling. As it is using WM internal event system, it should work regardless of OS language, installed dialer etc.