A group of users can be created with a purpose of receiving voice announcements through the speaker of a telephone set, but it has to be in the waiting mode.
Conference phones are meant for holding conferences between three and a
bigger amount of participants. This allows all participants listening and
speaking simultaneously. Usually the conference is begun by the participant
having “Conference Phone”. Other participants call to a special number for a
conference which connects them with “Conference Bridge” that joins all lines
together.