Samsung Galaxy SII User Manual page 79

Viewing Missed Calls from Lock Screen
When you are unable to answer a call for any reason and
your screen is locked, the number of missed calls are
displayed on the Lock screen immediately after a call is
missed.
1. Press (Power/End) to reactivate the screen.
2. Touch and drag the button (with the number of missed
calls on it) anywhere on the screen. The Logs tab is
then displayed.
Call Functions and Contacts List 74