Simply tap the End button on the Call screen to end the
call.
If you accessed other device functions while the call was in progress, there are several ways to return to the Call screen to end the call.
Press the Home Key , tap the Phone icon
(in the QuickTap
Bar), then tap the End button
on the Call screen.
Press the Home Key , tap the ongoing phone icon
in the upper-left corner of the
Home screen, then tap the End button
on the Call screen.
Drag the Notifications panel down, tap the Phone icon (in the ongoing notifications),
then tap the End call button
on the Call screen.
You can also press the Power/Lock Key to end the
call, if you activated this feature in the Call settings menu.