Article ID: 978163
Consider the following scenario. A user is not enabled for Microsoft Office Communications Server. The user has a phone number that is published in the global address list (GAL). In this scenario, you cannot call the user by using the Actions button in Microsoft Office Outlook 2007. However, you can call this user through Microsoft Office Communicator 2007 R2.
Note When you double-click a user's display name in Outlook 2007 and you sign in to Office Communicator 2007 R2 at the same time, you can use the Actions button to perform additional actions. Some additional actions that you may perform are Call, Add to Instant Messaging Contacts, Reply with Instant Message, and so on.
To resolve this problem, apply the following update:
(http://support.microsoft.com/kb/976135/ )Description of the Communicator 2007 R2 cumulative update: January 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.