Automatically save conversations in Microsoft Office communicator.

Hi everyone,
I’m using Microsoft Office communicator, (v2005). Does this program automatically save all my conversations by default or do I have to manually set this up?
If automatic, do you know where these files are being stored?
I’m unable to find any history of conversations.
Please give your valuable answers, I tried to find answers, but I was unsuccessful.
Any help would be much appreciated.
