Sharp AQUOS Crystal - Manual (Page 112)

Phone App 103
In-Call Screen Layout and Operations
While you’re on a call, you will see a number of onscreen options.
Screen Auto-Locking During a Call
Your phone’s screen automatically locks during a call to prevent unexpected touch screen operation.
To operate the screen, unlock the screen as follows.
1. Drag the Unlock slider down in the locked screen.
The in-call screen appears.
In-Call Screen Layout
Touch options to activate them during a call.