Lync-Skype connectivity gives Microsoft Lync users the ability to communicate with hundreds of millions of Skype users worldwide. This enables Lync customers to take advantage of the global reach of Skype to connect with suppliers, customers, and partners—while still relying on the enterprise richness of Lync.
Lync users connecting to Skype: Lync users can connect to Skype from Lync Online, Lync Server 2010 or Lync Server 2013 using the Lync 2010 or Lync 2013, desktop clients and any of the Lync 2013 mobile clients.
In order to connect their Lync users with the Skype community, Lync administrators first need to enable Lync-Skype connectivity. Information on how to do this can be found here for Lync Server. For Lync Online, connectivity can be turned on from the Lync admin center within the Office 365 portal.
Skype users connecting to Lync: Currently, to achieve connectivity with Lync, customers must install the latest Skype client for Mac or Windows. Skype customers will also need to sign in with a Microsoft account. If they don't have a Microsoft account, it's easy to create one. Customers can merge their existing Skype account with their Microsoft account for single sign-on across a variety of applications and services.