Within the Schedule Settings tab, set values in the Scheduling Parameter section which apply to most customers of your organization.
You can deduct the meaning of these settings from the User Manual!
The Field is part of the Custom Object PTCustomerCallSettings__c. It is possible to select any numeric Field (with 0 decimals) of the Object pt__CalculatedCallIntervalDaysSample__c. This mechanism enables you to calculate the customer Call Interval of your organization with the help of a formula field (see section Calculated Call Interval).
If you already have selected the Field of the Call Interval as PTCustomerCallSettings__c, undo the check box Default next to Call Interval, select Calculated and choose the relevant Field:
For customers, where the desired Call Interval is set to Calculated, the Call Interval will be read from this Field.