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.
In telecommunications the automatic call-back is a computer telephone function which allows the user by the engaged addressee’s line or in the other case of the subscriber’s inaccessibility indicating the system to save the number of the called subscriber and make the call when the line will be available or when the called number is not engaged.