Microsoft Lync is a robust communications tool that is included in the Office 365 suite. It provides instant messaging capabilities, PC-to-PC audio/video calling, and online meeting capabilities. It also establishes user presence.
To install Lync, logon to http://portal.microsoftoneline.com and click Install Lync from the portal home screen.
For PC users: Lync can be configured to automatically start when you launch Windows and it will run in the background. To launch Lync, click on this icon in the system tray in the bottom right corner of Windows:
For Mac Users: Once Lync is installed, it needs to be manually configured to connect to the server. Open Lync, choose Lync>>Preferences>>Account and click on Edit in the Advanced Server Settings. Click on manual server settings and use <sipdir.online.lync.com:443> for both the internal and external server names.