Term: What is a Matrix "Virtual Party-Line"?

A virtual party-line (or conference) is like a standard telephone conference.
When person A speaks—everyone hears them, when person B speaks everyone hears them.  To participate in a party-line a user with a Station needs a key programmed to talk and or listen to the Party-Line (Conference).Interfaces can also be assigned as members to a party line but they are normally made as permanent members.