Creating a Custom Report type with activities as the primary object is the recommended way to create a report on agents' daily call volume, including related case and contact information. A Custom Report type is a type of report that allows you to select the objects and fields that you want to report on, as well as define the relationships between the objects. By selecting activities as the primary object, you can report on the calls that agents have made or received, as well as filter them by date, duration, or status. By selecting case and contact as related objects, you can report on the details of the cases and contacts that are associated with the calls, such as case number, case owner, contact name, or contact phone number. Verified References: Service Cloud Consultant Certification Guide & Tips, Create Custom Report Types