Number of sessions

[learning_2_excel]

I am trying to create a report where I can show the number of calls happening every 30 mins, if a call is running is more than 30 mins then it should also reflect in the next 30 mins. I have 4 columns A,B,C,D having start date, Start time, End date end time. We can exclude the date since I want to show the utilization in the 24 hour window. Example:
Time Intervals Number of concurrent calls
12:000AM - 12:30AM 6
12:30AM - 1:00AM 15

Sample data below:

Start Date Start Time End Date End Time
6/9/2015 12:02 AM 6/9/2015 12:02 AM
6/27/2015 12:10 AM 6/27/2015 12:15 AM
6/27/2015 12:16 AM 6/27/2015 12:24 AM
6/9/2015 12:18 AM 6/9/2015 12:21 AM
6/9/2015 12:22 AM 6/9/2015 12:22 AM
6/23/2015 12:30 AM 6/23/2015 1:38 AM
6/30/2015 12:32 AM 6/30/2015 12:32 AM
6/9/2015 12:33 AM 6/9/2015 12:33 AM
6/9/2015 12:33 AM 6/9/2015 12:33 AM
6/9/2015 12:33 AM 6/9/2015 12:33 AM
6/9/2015 12:33 AM 6/9/2015 12:33 AM
6/9/2015 12:38 AM 6/9/2015 12:38 AM
6/9/2015 12:38 AM 6/9/2015 12:38 AM
6/9/2015 12:38 AM 6/9/2015 12:39 AM
6/25/2015 12:41 AM 6/25/2015 12:41 AM
6/23/2015 12:46 AM 6/23/2015 12:46 AM
6/23/2015 12:46 AM 6/23/2015 12:46 AM
6/23/2015 12:46 AM 6/23/2015 12:50 AM
6/23/2015 12:51 AM 6/23/2015 12:59 AM
6/1/2015 1:00 AM 6/1/2015 1:01 AM
6/23/2015 1:01 AM 6/23/2015 1:13 AM
6/13/2015 1:03 AM 6/13/2015 1:05 AM
6/13/2015 1:05 AM 6/13/2015 1:08 AM
6/23/2015 1:14 AM 6/23/2015 1:15 AM
6/30/2015 1:20 AM 6/30/2015 1:20 AM
6/30/2015 1:23 AM 6/30/2015 2:15 AM
6/30/2015 1:23 AM 6/30/2015 2:15 AM
6/22/2015 1:25 AM 6/22/2015 1:26 AM
6/22/2015 1:35 AM 6/22/2015 2:40 AM
6/16/2015 2:01 AM 6/16/2015 2:01 AM
6/16/2015 2:02 AM 6/16/2015 3:03 AM
6/25/2015 2:04 AM 6/25/2015 2:06 AM
6/25/2015 2:06 AM 6/25/2015 2:06 AM

[JeteMc]

Here is a table that yields the counts that you prescribed for the sample.

Call Log Times.xlsx

Hope this helps