Cancelling queued calls will 'unschedule' all the calls queued up for today. You can verify the campaign has been cancelled by checking the campaign status has changed from 'queued' to 'unscheduled' in the campaigns table.
This feature is available for use when you realize you have scheduled the calls by mistake. If you want to re-deploy the calls, you will have to manually do so by scheduling each campaign individually using the 'Schedule New' feature in the Campaigns panel.
Cancel queued calls