Click on the icon  to activate the Power Dialer.

You will get now an option to select a call campaign.

is a personal call campaign (typically used by sales or administration)

 is a group call campaign shared with multiple users (typically used by call centers)

The number in red brackets indicates the number of pending calls - calls which are due (without a due date) or overdue (with due date). Calls that are scheduled but are not due are not indicated.

After selecting a call campaign, you get 3 (personal call campaign) or 4 (group call campaign) TABS.