Lync Server 2013 will continue to provide the integrations with Exchange that existed in previous versions, and will introduce several additional integrations as well.
All the new Exchange integration features offered with Lync 2013 also require Exchange 2013. Therefore, an organization must upgrade both products to the newest versions in order to use all the Exchange integration features.
Continuing in Lync 2013 is integration with Exchange Outlook Web App (OWA). Lync and OWA integration allows Presence and IM capabilities within an OWA session, and includes the following useful features:
• Presence for internal and federated Lync Server contacts
• The capability to start and maintain chat sessions directly ...