Conference Bridge connects a number people participating
in conference-calls. It represents itself a server that works as a telephone
and can respond to many calls simultaneously.
Gatekeeper is an administrational tool for H.232 multimedia networks. A single unit can control interactions for each zone, which comprises the terminals, MCU's and gateway within the frames of a particular domain. Gatekeeper is an optional element, but when it available, it becomes the central administrative entity.