Mitel Phone Manager is a great tool to have on your PC allowing you to take complete control of your phone without having to touch it at all. One of these great features is being able to access your voice mail and also see notifications of who has left you a message.
The voice mail icon is displayed in the main window in the top left hand area (image below), if there are any new messages left there will be a red circle displayed on the icon with a number inside. That number will tell you how many new messages there are.
If there are multiple messages from different sources such as an individual and group voice mail box clicking on the icon within Mitel Phone Manager will create a drop down of each mail box and the number of messages in each one. By clicking on the message you will be instantly dialled into message retrieval for that mailbox (you may need to enter a password for that particular mailbox).
Once you have read all your messages or there are no new messages there the icon will not have a red circle over the top of it.