It looks like your using a table format, but I think you might be better suited to using a chart.
You can have the y axis being the Call owner, and the x-axis being the (sum of) Call duration, and then sort the y-axis by Call duration.
Is that viable?
Here is a Chart type report, but with the same problem:
I cannot see how to sort the Y-axis groups (“Call Owner”) according to values associated with the entities - can only sort by the entity Names.
In this chart I am grouping Calls records by associated Call Owner. In this case I want to sort the GROUPS (the Call Owners) by the SUM of the group’s associated Calls’ Call Lengths field (Secs in the Y-axis chooser).
You can see what I’m trying to do - sort the Salespeople (the groups) from most to least productive, as measured by their total Call times.
In your first table, you hadn’t broken down the call length into groups so I assumed this wasn’t needed.
In the chart, remove the Secs field from the y axis, leaving only the names, and make sure the x axis is the sum of call duration.
Then you can apply a sort to the names on the y axis where you don’t sort by name, but by the duration sum.