If you're busy and don't want to be disturbed, you can silence incoming calls with the do not disturb feature. When enabled, callers hear the busy treatment. You can also enable a ring reminder to play a brief tone on your desktop phone when you receive an incoming call while on do not disturb.
Go to https://settings.webex.com and select Webex Calling.
From the Calling User Portal, click Call Settings.
Toggle on Do Not Disturb.
Check Use ring reminder, to be notified by a sound when a call comes in.