Duration time is calculated from the time a contact comes to the user's desktop until the time the contact is resulted.  The time is stamped in Call History at the same time the contact is resulted.

If a contact spends time on your desktop but is never resulted then no duration is recorded.  Examples of this would be when you search a contact to view and then leave or if VanillaSoft times out with a contact still on the screen.

Note: This time calculation is no way related to length of time on a phone call.  That time calculation should come directly from your phone system.  Please ask your phone vendor for this report.