You probably know about the Dynamics CRM Lync integration that allows you to see presence notification for contacts and users and allows you to click on a phone number to initiate a Lync call. But there are also additional integration points that are possible if you also use CRM for Outlook:

• Conversation tracking: Whenever you have a Lync conversation, your conversation history is stored in a folder in Outlook. These conversations can be tracked just like emails.
• Voicemail tracking: If you have the voicemail/missed call notifications sent to your email, these can also be tracked. There was a bug affecting deployments using the email router to track incoming messages where the tracking of voice mails no longer worked after upgrading to Exchange 2013. This is fixed in CRM 2011 UR 16 and CRM 2013 UR 3.