Samsung Galaxy S6 edge +

When you have an ongoing call, the new call is signalled by a sound.

Press and drag the accept call icon right.

Press Put ‹phone number› on hold.

The new call is answered and the active call is put on hold.

Press Swap.

Make sure the call you want to end is active.

Press the end call icon.

The active call is ended and the call on hold is automatically activated.

Press the end call icon to end the call and return to the home screen.