what program in Linux?

[Karen Lewellen]

would allow you to participate in a live online conference?
I almost sent a copy of the invitation so you would understand what I mean. 
I do not mean messenger programs, but programs that allow you to use a 
microphone and communicate with others on line.  A variation is programs 
that allow you to communicate in a room set aside for this purpose even in 
text.
If my question is not clear, I will post the invitations so you understand 
my meaning.
Karen