Load the data without the Time field, instead convert this to an Hour.
Add a Count(Time)
and group by the Date and Hour.
You will then have a count of calls per hour per day
(You could do this in a measure in the app by adding a calculated dimension to create the hour and counting the times, but depending on what you want and how many calls per hour you get it might be better to calculate it in the script)
I converted the time field into an Hour
This way I was able to create a table with Hour as dimension, with a count Trunk as measurement.
This gives an picture about the total number of calls received on this date.
But when I use the Trunk average as measurement, the results are all over the place.
(Trunk is a unique key to identify each call)