To end the callback call and get immediately ready you select the appropriate feedback and click on End call & send feedback.
For a two step procedure, click End or e to end the callback call in progress, then select appropriate feedback during the following Wrap-up, and click Send feedback.
If you are working in Light Mode you put down the receiver of your telephone. However, the contact is not ended until you pick a feedback in ACE Interact, in the same way as described above.