It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
Feature allows subscribers calling to a certain number in order to connect to a conference call. The one, who dials the number, will connect to the conference. However as a conference controller one should give that certain number to all the participants and set the time for conference in order for the participants to be able to set up a successful conference.