I have seen the use of Outlook Plug-in for Web Dialer in a demonstration. This allows pressing an icon in Outlook and dialing the phone number of contacts stored in outlook address book.
Where can I get such plug-in?
Actually this plugin is called Cisco Telephony Service Provider (TSP) and it's available from the configuration web page of Cisco Callmanager.
From the menu select Application>Install Plugins.
You can find more information in the following link: