Class 4 provides a very comprehensive filter for you to look up CDRs that you are looking for. To search for CDRs, you go to Statistics > CDR Lists:
Then, you can see all the search criteria:
Class 4 gives you complete set of fields to view your CDRs:
If you are search for CDRs within a long period of time, it may take a while. Class 4 let you run your CDR search job in the background by selecting "Excel CSV" option.
When this option is selected, your CDR download will be available in the Export tag when ready: