Mitel Connect app allow you to create instant Conference Calls, by just adding users to a normal currently call without losing connection. Please follow the steps below:
To open the Mitel Connect app, You just need to click the icon 
and it will open windows like the pictures below.
1) The first step will be make the first call to one of the user you desire to have in the conference.
2) Then, Once the user are in the call. You will have the icon below to add more users to the call (you can add as much as you want).
3) Once you add all the user that will be in the conference, please select the option Conference and all the users will be add it into the call.
Please if you have any question Contact IT Team by our Support Portal.
Regards,
IT Team