If the voice mail system is Cisco Unity Connection, there is the CUMI
API, designed to allow applications to receive notifications of, browse,
and access voice mails:

http://developer.cisco.com/web/cuc/home

Note, the HuntPilotDN is not a 100% indication of voice mail, unless you
already know the hunt pilot for the VM system is part of the call flow.
Hunt groups/pilots can be configured for other things (like phone pools)
as well, and the HuntPilotDN would have a value for those call flows.

You might be able to try some forensic tricks, like checking to see if
the call eventually went to a VM-associated DN where messages are known
to be recorded, or comparing the length of the call with the length of
the voice mail greeting (longer calls suggest a message was left.)
These are not going to be be fully reliable howerver, of course.

Dear Shivinder Sing,
I need you support because I'm developing a basic C# report system that show few information from a CDR-csv dump imported into SQL.
I have problem to calculate the call duration, calling number e called number etc...
 
Can you give me a little help to understand how correlate record in CDR-csv dump?
I already read each document that I found but without success.
 
Thanks in advance.