Hi all. I would appreciate it of you could help me write a query. I have a table like this one:

The end result I would like to be like this:
(Sum of calls based on duration)

The duration column does not have fixed duration but I want it to be created based on the data that I have. For example if one call has 52 sec duration then the duration column should have data until it reaches the 52 seconds mark (51-55):