The Contacts tab provides you an overview of all the contacts in your organization and provides a status indicator.
A green circle displayed next to a user’s name and extension means that user is currently available. A red circle means the user is currently unavailable as they are already on the phone with another user or set their status to Do Not Disturb. Clicking on an extension will bring up a new window as seen below, where you can call the contact at their extension, their work contact, mobile number, or their home contact number. You can also leave a voicemail for the contact as well.