To accept an invitation to a 3D Conference, in the
Invitation dialog box, click the Accept button.
You are now considered to have joined the meeting.
To refuse the invitation, press the Respond
button, enter your answer in the text-entry field of the Instant
Messaging dialog box that appears and press the Send
The message is sent to the creator of the meeting explaining your reason
for not accepting the invitation.
To ignore the invitation, press the Close
The dialog box will be closed.