To report the average number of days that Cases stay open, creating a formula field on the Case object to calculate the age of each case is effective. This formula can calculate the difference between the case creation date and the current date (for open cases) or the closed date (for closed cases). A report can then aggregate this data to calculate the average age of cases, providing insights into case resolution times.

In the build phase of a Service Cloud implementation, prioritizing the configuration, development, and testing of the application in a sandbox environment is crucial. This ensures that the system is aligned with the client's business processes and requirements before deployment, facilitating a smooth transition and successful implementation.

Open CTI features can be made available to users when building a Lightning App using the App Manager by adding them on a utility bar of the Lightning App or on a record Activity Feed list. A utility bar is a fixed footer that displays utilities (such as Open CTI SoftPhone) as icons in a panel at the bottom of every page in an app. Users can access Open CTI features such as making calls, receiving calls, transferring calls, or logging calls from the utility bar. An Activity Feed list is a component that displays all the past and upcoming activities related to a record, such as tasks, events, emails, or calls. Users can access Open CTI features such as dialing a phone number or logging a call from the Activity Feed list. Verified Reference: Service Cloud Consultant Certification Guide & Tips, Add Utilities to Your App's Utility Bar, Add Activities to Your Lightning Pages