If you’re already working on a Surface Hub and want to add a conference call, open Skype for Business, then select the Call button. If you know the person's phone number, select Make a phone call.
To find the person, select Search for someone, then type the person's name.
When you've found who you want to call, select the person. To add more people, search again and select each person you want to add to the call. To start the call, select Invite.
If you’re already in a call and you want to add a Surface Hub, see Add a to an already scheduled meeting.
If you’re using a Surface Hub, and you need to join a call that’s already scheduled, see Switch to a new meeting or session.